Breach of contract & irregular debit amounts

My mother installed a tracking unit in her car late last year. The agreement that she made telephonically with the agent that was assisting her wad that she will get debited R100 ONLY!, however she is now being debited R258. How so when that was not the agreement? Are you guys ****ming her because shes of elderly age?? We called Matrix to resolve this issue & request the recorded phone call which will clearly state what agreement was reached, but nothing. You people keep telling her you will call her back but never do. I am sick and tired of this cause this is my mother’s hard earned money & you lot are ****** ****mers. Fix this or cancel the damn contract!