Unfair Suspention of mobile line

We recently opened a contract with MTN in the middle of August. We have not received any statement of account to say that an amount was due for payment at the end of August and also the contract has a debit order arrangement, which the account was not debited for. On the 11th of September I received a message on my phone from MTN to say that the line is going to be suspended and no outgoing calls or services will be available. To date i cannot understand why we were not sent a message prior to the suspension to let us know a payment is due. I am very irritated with this situation. I have logged two complaints of this matter on the MTN website and to avail, no response from MTN has even been made.