Bridge of contract

I got a message from cell c that my account is on arrears I called the number on the sms asking why was the amount not debited on the agreed date they said the problem is on their side yet we had a contract that debit date is the 23rd not they don't answer my question saying it's their side n gave me a number to call their debit order department and when am calling the number seem to be not working because I paid the money now they don't care answering my question.