Happened to me a couple of times many years ago when still new to punting and a bit naive. Once asked for change, got my £5 and then has a crap punt, and I mean super crap, because she was pissed about it. Second time wanted to make a point and walked.
Now anal about it and always have correct money after agreeing services / cost in advance. Did once pay with 5 x £1 coins and the Rom wasn’t happy but probably wouldn’t have been happy regardless!