Bad service

I have been struggling to cancel my contract even after following their instructions of giving a 30 day notice then the contract should be canceled But was not done and no one seems to be interested in helping they are just calling to sell more and tell me about my balances for contracts that were even falsely advertised to me. I have been fighting this battle from November till now no one can seem to be able to assist me I've been sent from pillar to post.