was billed thrice in one month for internet servic

I app**** for internet end Sept nd was billed for it thrice in October. I queried it in October but thet took their time passing the credits. My debit order has a ceiling of R250 pm so I would just pay them the difference I tcalculated to be correct. I still don't want to change the ceiling amount because telkom is taking their passing the credit. Final one went through in December. Also, in the meantime my service was cut and I was charged for reconnection. I do not want to pay it because telkom took their time passing the credits. I had a call from them yesterdat to pay the outstanding otherwise the service will be cut again. Was even told that I will be handed over ! I am prepared to pay only what I owe them and no more! I actually wish that I could have handed them over for taking their time to pass those credits