Telkom is useless. Don't use them. Ever

Took out a 24 month contract a few years back and my account was changed to a month to month contract in 2017. I decided to cancel my contract from the end of November 2018 and on the 15th November 2018 I used the online system to cancel. Received notification that it is being processed. 1st December comes and I am billed again. Go in store and they say that I won't be billed again. Now the 1st January comes and I am billed again. Online says the contract is cancelled but yet I am still billed. I demand a refund for December and January