Telkom is a ****

I had a contract for 24 months with Telkom SA after having to bear with their poor network for 2 years the contract came to an end in April and I got rid of their simcard but they are still debiting my account and when I enquire they say I did not cancel the contract but 24 months has lapsed. So I am paying for a service that I am not receiving as I have gotten rid of the simcard.