Telkom endless debits giving you - balance at the bank.

I have done a data contract with telkom which was 318 a month. Now I have to pay 1740.00 which I used 2 months service of 636 and now I have to pay 1740 cause there debits they kept Try to get from the bank. On return unpaid is more than what i ower and I have them again. For there endless debits which amounts to a R1000.00 now. Daylight *******.