There's a reason why everyone in Pittsburgh has a horror story about Yellow Cab. The service is absolutely horrendous.
I had surgery scheduled in the fall and it was so early in the morning that I needed a cab because the buses weren't running yet. I called Yellow Cab over an hour before I really needed to leave. I waited for an hour... nothing. Then I got a call that they were at my apartment... they weren't. The cab went to the wrong place. When I asked the dispatcher to please send him to the right apartment, she told me I'd have to place a brand new call for a cab.
I didn't have another hour to wait around, so I drove myself to the hospital. I had to leave my car there overnight because I couldn't drive home after the surgery. So yeah, that is just one of many stories I have of being stranded by Yellow Cab.