Karl, that's just life I'm afraid - we don't own customers.
If a prospective customer calls you and you don't want to take work from another then just ask if they already have a w/c and decline to do it.
If you do decide to take the job then you may have not picked up a loyal customer.
I really do not mind losing customers, if they are correct in what they say "blah blah is cheaper" then thats fine. No problems. Like I said I find canvassing very easy. Even on hard days I enjoy it.
But I want you to see the bigger picture if you can. If window cleaners make a habbit of selling themselves on price alone, and lets face it, if you can't even be bothered to knock the door to give a quote you are just selling on price, then what will the next window cleaner have to put on his flyer, and the next after him, and so on. It would soon dawn on them that the only way for there flyer to work anywhere near as good as canvassing is if they use the price as a hook. And big prices make lousy hooks.
The end result is it would become the fashion for window cleaners to sell themselves a cheapo service.