It was certainly no fun showing up ahead of time with a ticket that I had purchased 5 months earlier and being told by the bus driver (quite rudely, by the way) that the bus was full and that I would not be allowed to board! How can one have a ticket for a seat and be refused boarding???
After being pushed aside by customer service for 45 minutes they finally found another bus for me and two other people who also had not been allowed to board the bus that we had tickets for, and was lied to by the customer service girl when I asked if I would arrive in time for my connecting bus in Buffalo. Of course we arrived over an hour too late to make my connection and had to sit an additional 4 hours for the next bus.
No one apologized, no one did anything to make up for the inconvenience of being several hours late for my destination, and no one would answer my question as to whether they deliberately overbook their buses. Never using Greyhound again!