How did you resolve this, I have a couple of regulars who pay this way - but they send it at least a few hours in advance. It has to be there by the start of the booking.
I walked. Told him to not bother contacting me until he had paid for my time. Which was about 20 minutes waiting for him faffing about.
It was all last minute as he contacted me as I was on my way to say he had lost his card and could he transfer me. Being a reg I trusted he would do it. Thankfully I checked before we got down to it.
He did contact me a few weeks later. We met for coffee he paid for the previous visit for the full time. Bought me coffee and paid extra for that meet.
He apologised. He left, we were on good terms. Not really heard from him since.