LOL that's true (the backache)!
I didn't exactly kick them half my fee, but I tipped them very generously. I'm their band leader and hired them by the hour, so although the job didn't get done the way I had originally intended, it was still my band that got the job done and thankfully the client and musicians were all very happy.
The reason the client was understanding, is because everything was seamless. There was no panic, the show went on, the entertainment was great, and I've done in the past over ten flawless shows for him already...
Also, the client didn't really care what the entertainment was, as long as there was entertainment. So that was lucky...