J & J Mobile Auto Repair

I called these guys about repairing my *** alternator, which they did, but:
it took about 6 hours, and required the USE OF A SLEDGEHAMMER?? TO REMOVE.
in the process, they shredded the main belt, broke the turbo intake pipe, and eventually cost me nearly a thousand dollars to recover from.
so when they were done, the dude is all "hey look, we spent a LONG time on your car, how about a tip? several hundred is customary" so I tipped them just to get them the heck away from my car. when I asked for a receipt, the dude WROTE DOWN THE TOTAL COST ON A PIECE OF PAPER AND HANDED IT TO ME.