An embarrassingly high proportion of the big banks' current account customers are unhappy with their products or service, yet most aren't exercising their right to complain or take their business elsewhere.

In a survey of more than 5500 people by consumers' organisation Which? the largest providers all scored below its average of 62% for account satisfaction.

The results, published in its November magazine, reveal Halifax and NatWest did best ,with a desultory 61%, followed by HSBC on 59%, Lloyds on 56% and Barclays with 54%. The Royal Bank trailed in on 53%, Santander on 51% and Bank of Scotland came bottom with just 50%. The smaller Clydesdale Bank achieved a slightly above average 64%.

Which? executive director Richard Lloyd said: "These customer satisfaction scores should be a wake-up call for the High Street giants, who may soon find that, with quicker, easier switching, their customers are looking elsewhere."

In September, it became easier to change account providers, as the banks and building societies signed up to a guarantee that all switches would be completed within seven working days of the new account being approved.

All regular payments to and from the old account should be automatically moved to the new one, with the redirection continuing for 13 months so annual payments such as subscriptions aren't missed, and any fees or charges incurred because of errors during the process must be refunded by the new provider.

Despite predictions of a tidal wave of switching, according to the Payments Council, which developed the guarantee, only 89,000 people changed accounts in the month after it was introduced - just 9000 more than during the same period a year ago.

Laura Willoughby of independent campaigning website ­MoveYourMoney.org.uk, believes lack of knowledge is stopping many more people taking action.

She said: "People get very anxious when it comes to their finances. They don't know where to go and they don't want things to go wrong or to incur charges, so they do nothing. But if they spent a fraction of the time they spend planning their holidays on their finances, they'd find better deals."

The highest scorers in the Which? satisfaction survey were First Direct (85%), Smile (78%) and its parent the Co-operative (73%), the One Account (75%) and member-owned Nationwide Building Society (67%). However, First Direct, Smile and the One Account are internet only, so won't appeal to those who want branch access.

MoveYourMoney.org.uk, which aims to make people more aware of banking alternatives, rates providers on criteria including customer service, honesty and ethics.

Its top scorer, on 91%, is the Cumberland Building Society, which is open to Scots living in Dumfriesshire. Four of its next highest scorers - Reliance Bank, Coventry Building Society, Metrobank and Islamic Bank of Britain - don't operate in Scotland.

However, Leeds Building Society, which scores 79%, has branches in Glasgow and Aberdeen, and Swedish bank Handelsbanken, with 74%, is in Edinburgh, Glasgow, Aberdeen, Stirling and Perth.

MoveYourMoney's next best options include Nationwide, Smile and the Co-op. Those looking for an ethical option have traditionally chosen the Co-op, which however now looks likely to be taken over by a group of US hedge funds. The Co-operative Group remains the largest single shareholder, and chief executive Euan Sutherland insisted there would be no change in its ethical stance.

He said: "This bank will remain the Co-operative Bank. We are embedding the co-operative principles in the constitution of the bank to guarantee this."

Laura Willoughby said: "We will be re-rating the Co-op based on the news, but we're waiting for more information to see what it means."

Several not-for-profit, member-owned Scottish credit unions, including 1st Alliance (Ayrshire), 1st Class (for communications workers) and Grampian, also offer current accounts.

The Financial Ombudsman Service said current accounts were its second main source of complaints. Between July and September, it received a total of 143,177 new complaints, up 39% on the same time last year. Payment protection insurance accounted for the vast majority, but current accounts were the next biggest bugbear.

The service's chief executive, Natalie Ceeney, attributed the rise to a "mis-match" between what banks say they will do and their actions, and said they needed to start treating customers with "common sense".

If you are unhappy with any aspect of your account provider's behaviour towards you, put it in writing. Label the letter or email "complaint" and explain the issue briefly and clearly, including names of people you dealt with and dates of conversations. Enclose copies of any relevant paperwork, and say how you would like the matter resolved.

If the bank can't settle your complaint satisfactorily by close of business the day after it is received, it should send a written acknowledgement that it is being considered. You should be kept informed about progress and receive a final response - or an explanation of why one can't yet be provided - within eight weeks.

If it doesn't meet this timescale, or you don't accept its solution, you can go to the ombudsman service, which may award compensation if it finds in your favour. For more information, log on to financial-ombudsman.org.uk or call 0800 023 4567.