Yea, under advisement called that one. Under NO circumstances should you let them "clean" and rebuild your bearings after they've been pulled. Those things come sealed up, and are readily available, for a reason- no matter HOW good they clean it up, if a minute amount of crap gets in there, it can mean trouble, and added hassle for you.
http://science.howstuffworks.com/bearing3.htm
I'm unsure from your post if they actually pulled the bearing apart, or just did some external cleaning though.
It does kinda blow that you have to deal with them when replacing the front rotors (on the 5th gen at least) seeing as they go for around $30 a pop, and add extra time and hassle on. 4.8 hours though seems rather steep. And they still ended up hitting you for a bill TWICE what their estimate was for? Isn't the point of an estimate to give the customer an idea of what they can expect to pay? Most places I've gone to (if they give the estimate in writing) will STRIVE to come as close to it as possible, often honoring it, even if they weht a little over. I guess it all depends on how much the money means to you.