this is something that's on the rise all over the place - and your take on it is correct the claim that they are making is for breach of contract and is probably not one that they could win in court ('penalty clauses' are not generally enforceable under the law of contract) but these companies generally will not give up their case until you take them to court it's a low class business, but at the mo they're getting away with it as people rather pay than get drawn into endless correspondence with stupid people at tashy businesses in short, if you're up for a long dispute you can probably get away without paying, but you might have to stive off bailiffs along the way