Poor Service

I have received a couple of emails from Nu debt Management asking me to make a payment for my Telkom bounced payment for last month however I noticed that they have doubled the amount to be paid. I then queried and asked if they can correct the total outstanding and will do a payment. Nu debt has not responded to my emails. on the 22nd of May I then made a direct payment since it is almost the end of the month. Today they have debited my account and when I questioned the consultant at Telkom why they are debiting when payment was done? The response was that they have right to debit my account whenever they are funds in my account. This is so wrong and unconstitutional since they didn't respond to my emails. People are always willing to pay their debts however the service we receive from our suppliers is atrocious. :-(.