I keep a very comprehensive collection of receipts, PMs, and emails (no emails in this instance).
Also, the retaliatory feedback is uncalled for. I did absolutely nothing wrong in this transaction. I paid within moments of saying I'd do so, and was calm/collective/curtious this entire time. I don't see how it's "UNACCEPTABLE BEHAVIOUR"...
One would assume unacceptable behaviour would entail leaving a bag of flaming feces on someone's doorstep, or perhaps sending viruses to a disclosed email..... Hmm. I guess times have changed.