BBC One’s Inside Out programme ran a report on Monday investigating two firms which promise homeowners they will buy properties quickly.
Following the investigation, the Law Society has called on the government to increase regulation to protect vulnerable sellers.
Both Gateway Homes UK and its sister company Tom Craven Property, based in Leeds, promise consumers they can buy homes in just a week.
The BBC found there had been 40 complaints to trading standards relating to the firms including claims of delays and sudden price drops.
Whilst in advertising Gateway Homes UK said a sale could be "finalised in as little as seven days" however asks consumers to sign a contract allowing them a year to complete the deal.
Jonathan Smithers, from the Law Society, said tougher regulation was needed. He said: "We are talking about protecting vulnerable people and they need protecting. This sounds like an abuse and that is a very good reason to have more regulation."
In a statement, Gateway Homes UK said the number of complaints was well below 1% of its customers.
It said it offered "full transparency from day one" and the initial contract, which was separate to a formal sale contract, was jargon-free and easy for a customer to understand without the need for legal advice.
It said sometimes a revised offer was necessary after a surveyor valuation but the customer was free to walk away and that delays only occurred in a minority of cases.
David Lodge, a spokesman for West Yorkshire Trading Standards, which has received 40 complaints about the companies, said the most common complaint was in relation to the purchase price.
He said: "Other things include long delays. This company claims on its website it is going to take the pain out of selling your property but what people don’t always realise is that process can take up to 12 months and that’s actually in their terms and conditions."