Waisting valuable time and money

a round trip flight was booked for the 22nd of December. My grandmother was coming to visit me but I was admitted to hospital and my grandmother got sick as well as she is very old. We spoke to Thulisile who advised us we can just phone in and move the flight date that she would make a note. We phoned in a few times and always are kept on hold for at least 15min a previous time up to an hour. Finally phoning them to move the date they tell me that the ticket is not valid and the guy asked me if I want to make a booking on that light and then give me the full price, horrible service. I will advise everyone on the **** service.