MTN phone contract

Good day my mom had bought an IPhone 11 through contract from MTN in Greenacres, Gqeberha in 2021 April. The phone was for me, it was a surprise. The sales consultant that helped her didn’t explain anything to her. Her words were “im also as clueless about these phones, but I’m sure your daughter will know” at the time it was my first time owning an iPhone. my mom surprised me with the phone and told me it is to have 20GB of data, minutes and sms. Used the phone for a month or 2 then mtn consultants are calling her and telling her about a bill of R13 000 something of advance. She went back to the store to talk to the manager, manager also didn’t know what to say. She went back again there and the employee was no longer there and each time she’d go there she wouldn’t even get the manager. She called MTN and mtn said the account is no longer with them. As of today the 11th of March 2025 we still don’t know where the account is, what is the R13 000 advance from. Nothing feedback. Poor service.