Bad customer service

Had a product with vodacom that was canceled and returned on same day of delivery, but i still get invoiced and my account shows that it's in arears. I have a current data contract which i do pay for every month but they suspend it because of a problem from their side. It's been back and forth with vodacom for months now, service requests has been logged but still the problem persists. I've been a loyal customer for years but this is the poor service i get. Im being held accountable for an issue from vodacoms side and the problem is not being delt with.