Overbooked Greyhound Buss

I bought a Greyhound Bus ticket for Durban that was set to leave Johannesburg Park Station on Tuesday, 22 December 2015 at 13h30. It was also meant to be a double decker bus. However, upon arriving I found a single decker bus bound for Durban, which they informed me had been overbooked, and that I would have to wait for another bus which would take a maximum of 30 minutes to arrive. I waited close to an hour and no bus arrived! I eventually gave up on waiting for the bus and went back home. I feel that this is very disappointing service and believe that I deserve a refund!