I had a great experience with UBID! Well, I just got lucky I guess.

To make a long story short, we bought two speakers, one arrived via Fed Ex, but only one. So, we called and asked them what was happening etc. They said they would call us back, never did. Three days went by and I checked my credit card to see if they had charged us only to find out that they had credited my credit card for one speaker. Two days later the second speaker arrived via UPS. UBID had no record of it because according to them, it was shipped via Fed Ex. There was a Fed Ex label on it, but it had accidentally been picked up by UPS. There was also a UPS label on it but it was the one from one warehouse to the next. Anyway, we ended up getting 2 speakers for the price of one!
Also, my friend ordered a DVD player from them and when it arrived, the box smooshed on one side, so he decided not to open it and he called them. They told him they would call him back etc. A week later, they still hadn't called him back, so he called them. They said that a Fed Ex driver was supposed to come by to get it, but since he hadn't, the lady told my friend to just throw the DVD player away and she would credit his credit his credit card! Sure enough, they credited his card and he opened the DVD player and it works! Just a small scratch on the top!