On some days there were so many calls I would unplug the telephone.

Typically, I'd be sitting reading while my mother dozed, as she frequently did after she turned 100.

At the shrill ring she'd jerk awake, confused and disoriented. The volume was on loud to combat her deafness. She'd stretch a shaking hand to lift the receiver and then I'd see a look of confusion. I learned to take the receiver from her before the caller heard how frail her voice sounded, her thoughts still clouded from sleep.

Sometimes there would be silence that a nervous person might find threatening. Usually, there would be a voice, confident and authoritative, offering a loan or asking for personal details or suggesting money was owed to her and should be claimed.

When they'd finished their pitch I would say: "What you are doing is wicked. You should be ashamed of yourself. How can you bear to look in the mirror?"

One man rang back to tell me he had resigned. I failed to congratulate him. I viewed him and the rest as a pack of hyenas: misshapen creatures that lurk around the edges of society preying on the frail, knowing that they might be lonely and be pleased to hear another human voice with time for a chat.

The only consolation then was that the cold callers only seemed to have my mother's phone number. But now, it seems, elderly or vulnerable people are likely to be targeted by callers who know everything about them. It's a terrifying prospect.

According to an investigation by the Daily Mail yesterday, highly sensitive details of the pension pots of millions are being sold for as little as 5p and ending up in the hands of criminals.

When undercover reporters posed as a cold-calling company seeking to identify people with pensions to whom they could sell investments, the director of one data firm claimed he had access to the salary, pension pots and investments of one million people.

He supplied the newspaper's reporters with the pension and investment details of 15,000 people. He could also provide a detailed and complex picture of an individual's life.

How could he do this? Well, according to the newspaper, it's a by-product of companies having to keep their data bases of customers up to date and accurate. It's a laborious process and can cost £1 million to £2m a year. The firm visited by the undercover reporters did it free of charge in exchange for keeping all the data. The firm claimed to have such deals with 250 house-hold name firms.

These are your private financial details and mine.

Think about the information we hand over when seeking a mortgage, buying a large item by instalment or booking a holiday with insurance. By cross referencing, these unscrupulous people then know who has a healthy pension pot but is a bit short of income; who has kids reaching university age; who is in debt; and who is nearing end of life.

This disturbing revelation comes just a week before the big pension shake-up that will allow anyone from the age of 55 to have access to their money, to cash it in if that's what they want to do.

After these new revelations, it seems to be a disaster waiting to happen. The cold-callers are as plausible as they are unscrupulous. One man in his 60s told how he had a call purporting to be from a company in which he had owned shares. The caller knew when he had cashed them in and said there were a further 180 shares due to him. The company was willing to buy them and forward him the money. Could he just hand over his bank account details?

Fortunately he consulted his son, who spotted the scam.

Before knowing that personal financial data is sold on, I too might have fallen for it. I can see how it would seem like a bit of a windfall for anyone who was feeling somewhat hard up. It's not a huge sum of money. It's not unbelievable. The man on the phone wanted to buy, not to sell. Besides, if someone has private financial information like that, it makes it easier for him to sound genuine.

So who is to blame for this worrying state of affairs? Of course it's the criminals who are most at fault. They should receive the harshest punishments. This is not white collar crime. It destroys lives. It drives people to despair.

But there is another guilty party: the businesses and data companies that trade or sell on the confidential details of their customers' lives.

Under the Data Protection Act, it is legal for companies to outsource their customer data bases. However, the arrangement must be transparent. Customers must know what their information is being used for. Their consent must be freely given, specific and informed. It needs to be a positive expression of choice; not a failure to spot something hidden in the small print or omitting to untick a box. The customer should be required to consciously opt-in.

Scotland's Information Commissioner, Ken McDonald, said yesterday: "The ICO has powers to issue companies with civil monetary penalties of up to £500,000 for the most serious breaches of the Data Protection principles. Under certain circumstances, we can pursue criminal prosecutions although, if any of the businesses involved were based in Scotland, we would make a report about them to the procurator fiscal."

As I was typing those words my husband's mobile received the third text message of the day telling him he is owed money from mis-sold PPI. He isn't. Nor has he, as others texts assert, had an accident with compensation of £2,650 waiting for him if only he would return the call. Such calls are in breach of the Privacy Electronic Communications Regulations (PECR). But how is any individual to tackle such a breach? Instead my husband blocks the numbers - and every time fresh ones appear.

He can put the phone onto silent and ignore it. It's a bore, nothing more. But if he was frail and vulnerable it would be a different matter. He isn't sitting beside a landline, which is one of his few links to family. He isn't anchored by a phone which is his lifeline to contact the doctor.

Many in the older generation are faced with a conundrum. They need a secure income for the years they have left but interest rates are giving them little return on their savings. I can see why they might be tempted to hear someone out who explained the complexity of pension freedom simply and promised them a better return.

Looking forward, we can't allow it to happen. The sale of our private financial information is one of the biggest issues facing us. Yet it is on no political agenda.

Huge numbers of people could be defrauded. We can't leave it to the Information Commissioner. It's time for those competing for our votes to waken up and tell us how they plan to sort it out.