My drums on my 2003 Prowler are the same ones as when it was new. I have replaced the entire brake assemblies about 5 or so years ago, just because I thought it was time and the magnets started to look a little worn.
Sounds to me like they probably repacked the bearings, but I doubt they did anything to your brakes, except loosen up the adjustment on them so you would find they didn't work very well..
Then, they charge you an additional $80 for a new brake drum, but I'll bet they just adjusted the original brakes so they magically work again..
I don't have any clue what they did or did not do, but that's just my gut feeling from what I read, but I don't usually trust those kind of deals unless they show me the bad parts and that they have actually put in the new ones they are charging me for..
Good luck!
Mitch