I believe it depends on if its a personal loan or a loan given for a specific purpose. Probably something to do with the consumer credit act, no doubt someone on here will have more legal knowledge than me..which isnt hard really
Anyway, a friend was having their bathroom completely remodelled and was going to pay cash, the salesman offered them a discount if they took out credit as they got a kickback - the loan could be repayed as soon as the first payment was required and therefore both parties won.
Once everything was set up the company decided they had misquoted the price of the work and tried to ask for more money. The fact that my friend had signed a loan agreement turned in his favour as the contract was in fact between the loan company and the contractor and in the end they did the work for the original price quoted. No doubt they were leaned on heavily by the loan company!
Julian.