Telkom complaint

Am struggling to cancel an already expired contract with Telkom and if not done a specific way, which is just as difficult, they keep on debiting my bank account, and never mind the fact that this mobile router never worked when out of range. I have basically had my bank account debited for 2 years without any joy, and the more I want to cancel, the more obstacles are thrown my way. Whatever I have been told to do, I have done, but to no avail. Can somebody out there PLEASE help?