MTN

My partner has had a cell contract with MTN since around 1996...used as a business phone as well as private..the number is registered to our small tourism business for emails. There has never been a hiccup..BUT on the 4th of July the cellphone was Hacked?????or how did some black guys get into the MTN service to contact me and I was caught with them buying on my cellphone ---to the tune of R16493.57....we were totally unaware. We phoned MTN STARIGHT away and spoke to a person- it will be on a recording- who as we understood REVERSED immediately all these ******* payments. We are 79 and 75, and so not IT aware - we are not in a position to pay a phone bill of R19457.79..Why was this not reversed and surely MTN can do something about assisting us with this - we cannot go without the cellphone - it has all our SECURITY WhatssApp which are vital to our security being senior citizens living on a remote farm it is VITAL we have access to security via WhatsApp security on the cellphone, surely this should have and could have been reversed immediate as clearly the the number of those who put through the payments was listed. What can be done?