Failure to bill correctly and take debit order

We ported two phone numbers to MTN in March/April this year. At the time, we filled in the debit order details correctly on the application form. MTN subsequently inputted the details incorrectly. They then did not bill us for two months, and when they did, could not take the debit order off as they had themselves, inputted the wrong details. Last month, after not having initially been billed, we made a once off payment to come up to date, and updated the debit order details.<br> This month, once again the debit order details are incorrect and have not gone through! what is happening to MTN? When you call the call centre, it takes 30 minutes, and they still can't help you - and dont understand what has gone wrong! <br> MTN - THIS IS RIDICULOUS. Send us monthly invoices, and take the debit order off like you are supposed to! Your messages warning that we have not paid are insulting and poor corporate form - when the error is on your side! Your urgent response is required!!!