Bad service

Good day.My Sister who are living alone depends on her phone. Telecom implemented new wifi phones and she is getting no satisfaction from Telecom. As her new phone was sent to her on the 18th of Feb 2019 and having numerous problems to get her phone to work. After many calls to Telecom and speaking to every Supervisor we could phone....nothing was done. After more calls and doing everything they ask us to do....check the lines....put the sim in cellphone and tests we came to the conclusion that the instrument was faulty. Telecom took the phone and sim to relapse it with a new instrumental. After a long wait.....she received a phone just to discover that it was her old phone and nothing was done. After more calls still waiting for Telecom to assist her. Please help.