Flight doesnt care about its customers

I booked a flight with Flight Centre to travel from Jorburg to Harare and back to Joburg with my family. I then tried to cancel the flight on the Sunday we were meant to travel as i fell very ill and advised by my doctor not to travel but no one was picking my calls when i tried to cancel. I was then advised to buy a one way ticket the following day by one of you agents. When we attempted to get on the return flight we were told we were a no show and had to buy new tickets. So i was out of pocket around R15000.