Pre-paid number being billed

Early in June 2015, I went into the Menlyn Retail Park branch of MTN and completed instruction forms to change my last number over from a contract (which has already lapsed end of May 2015) from a contract to a pre-paid package.<br> <br> Now, 3 weeks later, I received a bill which still indicates that I have been invoiced for the new month of July 2015 as if the number is still under contract.<br> <br> After trying to call MTNs call centre to try and resolve the problem and holding on for more than 18 minutes without any success I have no choice but to lodge this complaint..<br> <br> MTN - Please note that you do not have any authority to deduct any amount from my bank account for this contract as the contract has been terminated early in June 2015 already. Should you proceed to deduct, I will instruct my bank to reverse the transaction.