Bigsky bus cancel my ticket

Booked and paid for 2 bustickets on Bigsky. Upon rrival after driving 2 houers i was informed my departe ticket was cancelled!!! I did not cancel my ticket, nor was i informed by bigsky that there was a cancelation, or is there written proof i have done so. I had to buy a new ticket resulting in me to have a shortfall on travelling fees!!!! It was humiliating.