Residents of a city centre development in Glasgow have been hit with enforcement notices telling them their homes are in breach of planning regulations and must revert to their original use.
The city council's action could mean the flats can only be sold on as student properties, leaving the owners facing a major shortfall.
One owner has already spent four-figure sums dealing with the problem, while another has been treated for stress three times since the issue emerged.
Those The Herald has spoken with bought their properties from banks after they had been repossessed and said solicitors and surveyors raised no concerns.
However, letting agents for neighbouring properties insist title deeds specify the flats can only be used by students.
Glasgow City Council said it served the notices after "receiving a complaint about breaches of planning control".
In total, 21 notices were issued to property owners on Blackfriars Road near High Street, on the eastern edges of the city centre.
The blocks had originally been commissioned by student property giant Unite before being sold to a property developer, Capital Invest.
This firm in turn sold rafts of flats to individual investors, who leased them as student flats. But with the property market collapse several years ago, many of the properties were repossessed and sold by banks in auction.
Amy Brown bought her repossessed flat from a major bank in November 2011 and said no restrictions of use were ever thrown up. The 33-year-old only became aware of the issue last month and has already spent in excess of £1000 simply establishing where the problem lies.
She said: "I'd heard rumblings, but as far as I was concerned this was my flat. I bought from the bank. It was all legally processed satisfactorily. There was nothing in the land register or any other restrictions.
"I've been in touch with property lawyers, and am now employing a consultant to put forward an appeal. So far that's been more than £1000. But if this goes against me and I have to sell, it's to a very limited market and will not get anywhere near the property's value."
Neighbour Gary McKay, a radiographer at the nearby Royal Infirmary, also bought from a bank.
The 26-year-old said: "I've been paying council tax since 2010 for the flat and as students are exempt, how didn't the council notice?
"The notice says we must fulfil the enforcement notice by next May. What happens then? This is my home and no-one has told us whether we sell up and get out or become landlords.
"We've had 21 people in the same situation. Are 21 solicitors and 21 surveyors wrong here?"
The council said that following an investigation into a complaint it "established that a number of the flats have been bought for mainstream residential use, which is considered to be contrary to the terms of the planning permission".
A spokesman said: "The fact that prospective buyers were not advised of the intended use of the flats is a legal matter for the owners to resolve."
It said the enforcement notice could remain "as a blight on the property", that it had no powers to evict people from their homes, adding: "The impact on the value of individual properties is not a planning consideration."