Cancellation of contract is nightmare

I have an on going issue with cancellation of my contract that ended in December. I've been sent from pillar to post, cut of a number of times while calling customer care eventually being put on hold and the finally the ended up putting me back on prepaid but the unfortunate part is to this day I'm still being billed few moths after. The sad part about MTN you'll continue running around in circles for them to cancel your contract. You would think as a customer you have the right to not pay something you legitimately asked to be cancelled. Mtn will gladly start sending negative scores on your credit bureau. It's the worst service provider would not recommend anyone take up a contract with them