I like the bit where you ask them to "kindly disregard" after you threaten them with court.
if they havn't paid by the time next clean is due I don't go back.
just do them when its raining
go and knock their doors. I chased up 4 late payers last saturday morning. All 4 payed up. 1 cancelled (result - mardy c*w) and one prepaid the next clean.
Remove garden goods to the value of, its quicker