My first upper purchase was from ADCO, along with a BUIS.
When I got the package, there was a giant hole in it, and no BUIS. (It was not a packaging issue, it was pretty obvious the UPS grunts had used it as some sort of launch ramp for something)
I called ADCO and they sent me another BUIS right away, no questions asked.
I would not hesitate to deal with them again.