Customer service is an absolute zero with this company. We went down to our pick up point (they gave a VERY general description of where you should be at our hotel) half an hour early to be sure we would make it. 10 minutes after pick up time we called to be sure we didn't miss it somehow, and turns out we did. They picked up at a completely different place than described. Instead of trying to help, the woman on the phone kept telling us we were lying and it was our fault. Eventually she suggested hurrying to get a taxi to the actual departure point, without giving us a name or address and hung up. We were not reimbursed the $30 extra for a taxi. Then we check in to wait for the bus, and the woman there was a nightmare as well. Totally distant, wouldn't hand us anything (instead kept dropping things right on the counter instead of my outstretched hand) and didn't ever smile, thank us, or sound friendly at all.
The only reason I give 2 stars is for the actual trip. The bus was comfortable, the bus driver was very knowledgeable and nice, and the trip itself was cool.
Basically, I would suggest taking the trip to Hoover Dam, but WITH A DIFFERENT COMPANY!