Refuse to cancel contract

I took a contract with Telkom for the past 2 years and it expired in Ocyober 2022 but was running on month to month basis. I went to cancel it at the shop and they also said I should call their customer service which I did. To my surprise the debit order went off. Today their sales person called and I asked them why they have not cancelled my contract he promised to investigate and call me back which he did not.

Now I am liable for 2 telkom contracts of which one was supposed to be cancelled.