A Mis-Representation Of An Upgrade With MTN

My mother has 2 x contracts with MTN - one number is hers, and the other number is mine. These are both on her name. In the last month or two, she received a call from MTN, and the customer service advisor was offering her an upgrade. My mother accepted the upgrade, on the condition that the monthly installment either remains the same, or is less. Upon receiving her bill for payment due at the end of May, we noticed that there has been an increase in the monthly installment. She's now having to pay between R700-R800, where previously, she was paying between R300-400. As far as I can tell, I think the upgrade was app**** to my number. I previously had a data only contract, where I received 2GB + 2GB promotional data every month, and now, I'm receiving 13GB data + 50 minutes. It is clear that the customer service advisor app**** an upgrade that is much higher in cost, going against my mother's conditions/stipulations. We are not prepared to be tied into a 24 month contract that was not agreed to, nor can we in any way, shape or form afford the increase in cost. I have attempted to call MTN 6-7 times now, and every time I reach the 7 minute mark in the queue, waiting to speaking to a customer service advisor, the call drops. I'm not sure whether MTN are experiencing technical issues. These contracts my mother holds with MTN - either they need to be adjusted to what they were before, or they need to be cancelled. I would like someone from MTN to treat this as a matter of urgency, and to make contact with me, within the next few working days. I would like to have this issues resolved, with immediate effect. Failure to do so, and I will escalate this to the Ombudsman. Firstly, what's happened here is completely unacceptable, and secondly, it's appalling that we're unable to reach MTN via their call center. Thank you!