To be honest you sound a bit clueless to me. I may be wrong of course, i'm just saying the way its coming across to me. You havn;t been round for three months, and you say he's going round knocking your customers ? Pound to a pinch of crap says they've rung him up, and he's found out you havn;t been for a few months and he's seeing who else has been left without a window cleaner. Of course, he could of rung you up, but then you could of rung your customers up and let them know..Unless of course you expect customers to wait for months with no window cleaner ? Either way i hope he's bigger than you and learns you a lesson not to treat your customers the way you have. And i'd guess by effectivley not servicing a customer for three months that you could fairly assume that you've give them up. He sold you monthly work ? At what point are they to assume you've left never to be heard of again...........2 months,6 months, a year ? Get your own act together.
A little harsh, perhaps, but I agree with CleanClear. Surely common sense would dictate that customers need to know if you are going to be missing several visits - their first assumption will be that you are like all the rest: "We used to have one but he just stopped coming and never let us know" - I'd like a pound for every time I've heard that!!
Regardless of your situation, your first priority should have been to inform your customers. This has happened to me a couple of times, and each time I ensured the customers were fully informed as to why I wouldn't be around for a while - I didn't lose any on either occasion.
When I'm canvassing people sometimes say "We've got one but he hasn't been round for at least 2/3/4 months." I feel quite justified in saying "I guess he's not coming back then, would you like a quote?" If he subsequently turned up and just started doing them again I would be the one complaining!!