Irritated

Please help and make sure I am never contacted by any of your people for a contract that was cancelled in August. It's still shocking that till today I am still being contacted and being told that my (Prepaid Line) will be deactivated, should I not make payment for my contract. The stupid contract is cancelled and wouldn't have been cancelled if it was in arrears. Upon the previous complained made, one of your people called me and said they will cancel the contract and that was done, so why I am still being called?! It's seriously not a customers problem to be teaching people who work for you why something or how something was done. Sort out your mess, before I even port my number out.