Usage Limit Not Set - Store or Network Fault

My company opened two mobile contracts with MTN.<br> This was done simultaneously, and I also had them place a usage limit on both numbers.<br> After a few months of use, one of the numbers received a hefty bill from MTN -<br> <br> I immediately returned to the store and requested an explanation. The manager at the time was Vishnu - He told me that the usage limit was in effect on one of our numbers, but that it was not in place for the other. When I enquired why, he told me that this was not a store fault but rather a network fault.<br> <br> Shortly thereafter, Vishnu resigned and was replaced by a new manager who had no prior knowledge of our case, so everything had to be explained to him afresh.<br> <br> I have made several attempts to reach Mr Aadil Khan (the Key Accounts Manager for MTN) in order to get this matter resolved and the new manager has sent several e-mails to him which are yet to be addressed.<br> <br> Customers cannot be held liable for a Store/Network fault - !!!