Return Flight Cancelled

I went to Durban for the weekend and had return flights booked i however found alternative transport to Durban and was only going to use the return flight. Upon my arrival i however was told my return flight was cancelled because i wasn't on the original flight<br> <br> How is this possible? Those seats was paid for by myself if i use them or not? After waiting for 30 mins for it to be sorted out i was merely told that i have to buy new flights and i have to decide because the check in counter was closing<br> <br> After investigating your very inconsistent rules and regulations words that contain \may"is mostly used as well as that my original flight retains its value"