Trading Standards has expressed concern over the quick-sale industry, saying that vendors could be at risk of losing large sums of money.

Alison Farrar, an investigator with industry regulator NTSELAT, said that there are “a few of these companies” on the radar at present.

She added: “I would imagine that there are quite a few more we don’t know about.”

Radio 4’s Money Box programme featured the quick-sale sector. Advertisements in national newspapers typically promise to sell people’s homes within seven or 14 days.

However, Money Box had examples where people have had the offer price of their homes cut, without their knowledge or consent, by tens of thousands of pounds.

One seller, Marianne Phillips, agreed to put up her home at £250,000, but says the company she used dropped the asking price by £20,000 without her knowing.

She has now put her home on the market with a traditional agent, but is concerned that her home may have been devalued.

In 2013, the then Office of Fair Trading published the results of an investigation into the quick sales sector.

Although it noted that sellers could lose a lot of money, the investigation found that quick house sales can be beneficial to consumers.

The OFT did however write to 120 firms operating in the sector to remind them of their legal responsibilities.

It also secured undertakings from four quick sale firms that they would improve their business practices, including “promising not to reduce conditional or final offer prices without a valid reason”.

The Property Ombudsman also has a code of practice for the quick sale sector, which applies to those agents who belong to trade body the National Association of Property Buyers.

The code requires that prospective customers must be told that the sale will be at a discount to the open market value. If the offer price is reduced, the reasons should be fully explained to the client in writing.