Many disputes arise due to statements or assurances made verbally during the negotiation stage, but not incorporated into a written contract. This does not mean they are not legally binding, but they are harder to prove. If you have been promised something which causes you to enter into a contract, which then turns out not to be the case, you can sue for breach of contract. If you have been told something which is an inducement to enter into the contract, but which may not be a fundamental part of it, you can sue for misrepresentation (Under the Misrepresentations Act 1967).
Where a supplier knowingly provides false or misleading statements and promises, this is a criminal offence and would have to be dealt with by the enforcement authorities (Trading Standards) who may or may not decide to prosecute.