Bad service from MTN call centre

It's funny how quick staff from MTN call Centre can get you to take out a new contract, because it is all about earning commission, isn't it. It does not matter that you are conning a 95 year old pensioner? MTN contacted my Dad re a new contract for my Mum, he pays for it through a debit order. Instead of continuing using my Mum's existing cell number they gave him a new contract with a new number, so all the free minutes, data and so forth will never be used? He specifically asked them what happens to her old contract, and they said it will be canceled. Today she tried phoning and found out she had no airtime, she was shocked. How is MTN going to rectify this problem. Mum is 84 years old. She doesn't have a dual Sim, or the knowledge of what to do next. Absolutely disgusting that a call Centre can do this. When her contract is up I will personally move her away from MTN for ever!!!!