Had one a couple of months ago. Banked charged me £6.00.
I went to the geezer and told him he needed to pay me the £6.00 charges alongside the original cost of cleaning the window which was also £6.00 (yes, I know). He started whinging saying his bank had charged him £20.00 and asked me to stand the bank charge myself!! I very calmly asked him why I should be out of pocket and effectively end up having cleaned his windows for nothing? He replied "well that's business".
He paid me and I now take great delight in walking past his dirty windows to clean the neighbours either side.
Cheers, Tom