I don't buy much digital music since I have a messed up CDJ and would rather put that money into vinyl, but all my digital purchases have been pretty good. When I burned them sometimes they did have a little cut off at the start, but I think that was my burning software since the file was fine.
I liked EDMDigital because of their compatible mp3 samples (instead of some proprietary format such as Real or Flash) and a website that wasn't 100% Flash.
A label would not send it that way every time. Maybe once a mistake, but I'm sure they'd correct it. They're giving you the run-around. I'd try another company to see how they are.
-Mark