I let all my customers know that I will not climb over fences, garages, flat roofs etc in order to clean the back.
They then usually try the "well, could you ring me so I can be in..!"
"sorry, it`s just not possible to run my round by appointment I`m afraid, I clean your area on such a day(s)...if you are in and can open the gate, I can clean the back...if not, I will clean the front only and the cost is £xxx"
Majority are happy with this, a couple have had keys made for me to open up gates and the odd couple or so have said "no thanks"
Makes me laugh when I am cleaning either side of their houses and their windows are filthy
I leave an envelope to all customers who are out to send me payment...I have had 2 who messed me about..they where both dumped after not sending payment for 3rd month on the run...got my money first though