MBD attorneys - your clients owes me money

MTN handed me over the MBD attorneys debt collections department, for monies they claim I owe due to their owns staffs illiteracy. I requested that they cancel my contract and my insurance, only for them to cancel my contract but leave on the insurance. After I noticed them still debiting my account I called and they confirmed it is for insurance, I then got so upset because I asked them to cancel it, but it was not done. I then asked that consultant to cancel the insurance and received an sms stating it will be done. The next month they still debited my account. I then stopped my debit orders myself. Now they claim I owe them. MTN is a *****, and MBD attorney should investigate the cases they accept for collections. I refuse to pay MTN, they owe me money, not the other way round.