Had a couch behider today, arranged 20mins b4 to pick up £10 for a front, "yes no problem im here" rang bell, no ans, rang mobile, no ans, hes been messing me about a few times now, so hes going to binned once i get my tenner.
anyway, was thinking of dirtying his windows next time im there, will be Cleaning his neighbours anyway so good cover, and leaving this note, what do you think?

Dear Customer,
As you have failed after numerous attempts to pay us a measley £10, we have refunded the amount back to you. please find the dirt which we removed back on your window. Sorry for any inconvenience caused.
ps, if you would like another number of a window cleaner you would like to rip off, please look in yellow pages.
Kind Regards
joe blogs
Dirty Window Cleaning Ltd Company No - 643123