If a customer of mine did that to me, they would be dropped.
I had a one-time customer who was schizophrenic. I was warned about him before I took him on as a customer, but thought I would give him a fair chance, as I can usually get people on my side by empathizing with and listening to what they have to say.
The first time, he was nice a pie, cup of tea, etc. Paid up on the nail. The next time, he asked what I was doing cleaning his windows, in quite an aggressive way. Alarm bells started to ring, but I stood my ground and explained that I was round a month ago, and he paid, etc.
He denied this and started being threatening, to the point of threatening to hurt me, and telling me he never wanted to see me in his neighbourhood ever again.
I told him that I certainly would not be darkening his door again, but would not be bullied into running away from my good customers (his neighbours).
His custom stopped at that moment, but I continued working in the area. He saw me whenever I was about, but never said a word or approached me again.
John.