Something is sus

I am writing on behalf of my neighbor. She has taken out a contract phone with MTN. She has claimed that when monthly payments were due, she was double debited. so she switched to manual payments. Now she gets charged 2 seperate payments for over 3 months. After enquiring with CS and going in to Cape Gate branch and dealing with legal and financial department, they have admitted to more than one bill but cannot find the reason for it.

Can someone please assist as MTN has switched off her connection without warning and now she can only use WIFI.