Can i cancel a mobile phone contract, as they have not instituted my new contract after 4 months?

I agreed to a new contract in october, it is now february and my phone company are still using my old contract terms. two phone calls later and they are still saying "adjustments next month".
Answer
Firstly cancel the direct debit - then call them back and tell them - then see how long it takes for them to get the contract out !they are taking the you know what..