Poor Customer Service

I've been trying to cancel my expired MTN contract since the 12th of June 2015 but no one at MTN can assist me. I can't get hold of anyone on the phone lines, I hold on for more than 40 minutes at a time just to get cut off. I've send numerous e-mails to customer care, they either respond with something totally different to what I'm asking after a month or they don't answer at all. After they confirmed my contract is cancelled they still deduct my premium. I've never experienced service like this before. I've send a written e-mail confirmation to cancel, why are they still deducting and cant assist me? Is this malicious and deliberate so they can take my money and not stop it? I'm not using the phone or the contract anymore, its paid up!!!STOP DEBITING MY ACCOUNT MTN!!!