Client pays for MTN incompetence

In December 2014 an upgrade was done. The previous package had a data usage limit of R100. This same limit was requested for the upgrade. After increasing bills, queries were logged. With little response. Finally it was established that the R100 limit had never been set . This was then set. After repeated visits to the main MTN store and the franchise store (different stores operate different systems which cannot be seen by each other!!) it was established which MTN employee processed the upgrade. This MTN employee admitted that she had not set the limit, as she was new at the job and did not have enough knowledge of what to do. I was told by one store that if the MTN employee admitted to not setting the limit, a written warning would be issued and MTN would refund me. The manager of the franchise where the upgrade was done says that this does not apply to their store and nothing can be done . I have paid in excess of R11 000, due to MTN negligence and incompetence with no responsibility being taken by MTN!!!! I've paid for their mistake. SCARY!