Telkom is *****ing via debit order

I had an expired mobile data contract and decided to cancel it. My first email with the cancellation form was sent 28 January 2016 without any response, I resend it and got a response 2 February 2016 that the cancellation request was received. Telkom still billed me at the end of February and March even though the contract was cancelled. In essence they were *****ing from me via debit order. My correspondence with them is that the contract was only cancelled on 10 March 2016. Opening a new contract takes 24 hours but cancelling it takes 38 days!!!