Bad Telkom Bad

Why is there always an issue when you want to cancel a contract, Telkom is the most messed up network ever, I will not recommend anyone to them, I cancelled my contract but yet Telkom want to debit extra, every first of the month they debit me, now they must debit me for the month of Feb on the first of March which is right but what I don't understand is why do they want to debit me again on the end of March when then contract is already cancelled and I'm not using any data