Hi Fez
We recently got a shop photographic shop because we were a customer, and they remembered us when their other window cleaner let them down.
To be honest, we find its a little bit more hassle than its worth. It has to be done every week, which means if we're on holiday cover has to be arranged. Also, it needs doing whether or not its raining, so you have to get saddled up for just half an hours work when you could devote the day to something else.
The cherry on the cake was when the regional manager phoned after we sent the first invoice moaning about the price!! (Which had been agreed in writing!) Their other guy was v cheap, but also v rubbish.
So now they're on very thin ice, just one more bit of hassle and its see ya later! (don't you love window cleaning for that freedom?!!)
One good thing though, while I was doing it, a chap saw me in the street and asked me to quote for his offices, which now make up our best contract!
Silly