Thanks for your patience. First of all the claims that they were offering the best rates in the country is not something you can necessarily challenge, as long as they have actually provided you with the rates they promised at the start. Claims of being the bets, cheapest, etc is something you need to satisfy yourself with, especially as this was a business to business contract. You do not have the same protection as private consumers, so if another business you are potentially going to deal with makes such statements, you need to satisfy yourselves that this is indeed the case. What mainly matters is whether they have provided the rates which they promised you at the time you entered into the contract.
If they have stuck to the promised rates, even if they were not necessarily the cheapest, then that would give you fewer rights to cancel. It does not prevent you from trying to cancel anyway and basically hoping that they do not go as far as court, but I they wanted to they can. If they do then it would be for a court to decide who has a case and in the circumstances it could be either to be honest.
I still suggest you use the argument of misrepresentation to justify the cancellation and if threatened with further action, state that you will oppose it precisely on the grounds of misrepresentation and breach of contract. Hopefully that will put them off from claiming but if they really wanted to they can still issue a claim and then as mentioned it would be for a court to decide.
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