Bad service

My mother has a cell C contract for more than 10 years, she is due for an update 3 months ago she was told she has to come back after 3 months. It's 3 months now and they are telling her stories. When I called the call centre after 18:00 as per the agent instruction. Now we are told to call tomorrow be 8 and 6pm. Can someone please call and help this is not fair. She pays her account with no interruptions.