Not an ideal situation to be in.
I had the owner of a '78 Super Beetle Cabriolet pass away while I was working on it. Unbeknownst to me, the owner had some serious health issues shortly after he dropped it off (he lived in the GTA area, 3 hours away) and appointed his daughter as POA. He didn't mention any of that the several times we talked.
She was a real piece of work. I had to sue for payment, but luckily, I had all my paperwork in order and I did get paid. Took almost a year, though.
Ironically, he was having the car redone so that he could present it to her on her 50th. It was her first car.
The last shop I worked at had the owner of a '56 Ford we were doing pass suddenly. Family pulled the plug and grudgingly paid what was owed up till then. The car is still sitting the way it left our shop... ;(