Dan, I see that as 10 hours to get the box out of the car, disassembled, bearing housings repaired (and I've no idea how they do that - and until they've got the box out they won't know how bad the damage is), box reassembled, back in the car and everything checked out. 10 hours doesn't seem like a bad estimate to me.
I'm damned sure I couldn't do it in 20 minutes, even with a fully equipped workshop: and I'm pretty sure I wouldn't want to cut corners on a customers gearbox. Reassembly, especially with new bearings, means shimming up the input shaft and layshafts again, not something you can do in five minutes.