I'm posting this through my custy's door in future 
Dear customer,, I cleaned your windows today and I was bloody freezing, I've had a real crap day because including yourself no one was home so now I'm going home skint, I also broke my flask when I slipped on this bloody ice rink I built you, so no hot drink for me today, Mr blogs at No 73 was kind enough to mention he would have given me a glass of whiskey to warm me up but he had no Ice :
So in my wisdom I've just just sold him a half ton block of the stuff but the fool paid me by cheque :
My brush is still frozen to your window so I can't do any more work anyway and I would be grateful if you could keep your eye on my brush for me, I've detached it from the pole so no idiot like the postman or your husband when he comes home from the pub half cut will trip over it.
Oh and another thing?...All the water I sprayed around the place has all frozen so your path is now the ice rink I've just mentioned, now it would normally cost you £20 to go to a proper ice rink but I've have been kind enough to build you your own personal one in your garden, so I think an extra £10 on top of your half done window clean isn't being unreasonable.
P.S.
If your husband does return home half cut and in his ultimate wisdom goes Arse over Tip then please think again before going to one of these no win no fee companies because I don't have a penny to scratch my arse with.
P.P.S
When my brush has thawed out can you just give that window a quick wash for me. 
Your ever loyal and friendly window cleaner.
very good jeff
could you reword it for cleaning in the rain
Well just a quick one before I hit the sack
Dear custy
Today, I was soaked to the skin at your property and although I was working in the torrential rain and I'll probably end up with pneumonia or at best the flu and believe me I suffer from man flu so its not funny and all this for the few measly quid that you be-grudgingly pay me :
so don't come out moaning that your path is wet because it wasn't my fault this time.
You may come home and find your windows are still wet and if you do then don't moan that the window cleaner with his brush on a stick left them wet because while you have been sat on your arse in a nice warm office earning £30,000 a year for doing nothing, I have to work in this rain and today I've only earned myself £10 and with all my overheads I'm already £50 down :
we have yet to convince a manufacturer to incorporate a umbrella into our poles so we can stay dry whilst cleaning in the rain.
I would normally wear my wet weather gear but the last time I was here your husband though that someone had thrown a condom out of your bedroom window, were in-fact it was me in my wet weather gear, so to save you any future embarrassment with your husband I no longer wear it at your property and because of this my wellies fill up with rain water.
I've also decided to add a surcharge on for any customer who moans about us cleaning windows in the rain and the reason for this surcharge is that I save you getting up out of your nice cumfy armchairs to water your shrubs and plants.
Don't think because its raining the rain will do the job because it doesn't give them as good as soaking as I do with my magic water.
People think that we window cleaners are the bottom of the pile and we are thick were in-fact are job is an art in its self and we have to be very clever to work out some facts like, Water freezes at 32 degrees and boils at 212 degrees. There are 180 degrees between freezing and boiling because there are 180 degrees between north and south now can you see why I have to work in the bloody rain??