Cancel the direct debit and forget about it.
I would suggest that would be the least likely, you still have a contract with them, so if you have 9 months remaining and you cancel your DD they will most likely transfer it to a debt collector. They won't go under and will probably 'buy' the debt so if you dont then pay you will probably end up wuth a CCJ registered against you.
I would write to them saying they have broken the terms of the agreement by not allowing you to watch what you origianally signed up to, therefore any contract is null and void, give them 14 days notice.
I notice on their website one of the questions is : Shall I cancel my DD, and the answer is no, they're hardly going to advertise the fact they broken terms of your contract and yes you should severe all ties immediatly.