Cell c 's ********* conduct

My mom was called by cell c in march this year to upgrade her contract over the phone which she agreed to because she was told it would be free of charge, compared to having it upgraded at a cell c branch because she would be charged....they proceeded with the upgrade and she received her phones and all was well. To her surprise she was debited R600 and something this month opposed to her monthly installement of R178 ×2 as agreed .....she then called them and they said the person who upgraded her didnt disclose certain fees that they had to charge her for the upgrade and theres nothing they could do to help her..... like how is this even fair? The old woman is working hard to feed her children to be ****** by cell c like this....we want them to listen to the recording and deal with this and also reverse the money they took without even notifying the contract owner or we are taking them to the ombuds.