Pathetic Servise

I have had a contract with Vodacom for many years. Last year I lost my job and could not pay my account. I therefore went to see them and I cancelled my contract and made arrangements for monthly payments. In January I made the last payment. My contract was paid up to date in full and final settlement. They then ignored this instruction and just switched the phone back on and started with a new contract. As soon as this happened I started contacting them to stop it. They then said I never cancelled the contract even though I never used it for approximately 8 months while paying if off. I then had to cancel it again with a months notice. End of January the contract had to end again. We made payment and the contract just continued with a few different numbers on my account. I have queried it went to the frued division and to date I can not get rid of this contract. They charge me for a handset which I dont have and a contract that I never asked for. How do you get rid of Vodacom. I again have an outstanding account now which I refuse to pay. They have switched my phone off and cannot use it. How do I end this??