Waste of time petrol and bank charges

I cancelled my contract on the 20th of March via email which they acknowledged. On the 20th of April after they deducted money from my account I went to the Benoni Telkom branch to cancel as I did not understand why they were still deducting. I was reassured it was cancelled. I went during the May of month to the carnival mall branch to verify if the account was cancelled, to my surprise I was told there that Telkom is still loading data on the cancelled account.

Can Telkom just cancel my contract. I don't want it anymore and it's costing me money having to go reverse the funds from the bank.