I had the same thing happen to a (much cheaper) 256MB USB flash drive. Hopefully, the actual circuit board wasn't broken in the process, and if it was, hopefully the actual components didn't break. If the components are still OK, you can simply use a soldering iron ($5 at RadioShack) and some solder to re-attach the plug. It's easy, just plug in the iron, wait until it gets hot, touch the iron to the solder, then touch it to the USB plug pins on the circuit board.
However, if you don't want to do it yourself, I don't know of any "firms" or places that will do this for you. Your best bet is to find a friend or neighbor or someone who has some skill with soldering or electronics repair, and if you can't find anyone, you can try an electronics repair shop or something.