I only have one service too…I also give out personal quotes and have been thinking of changing to a phone quote, but every time I think of all the possibilities and combinations of charging(screens, paint over spray, storms, multi-levels) I kinda like scoping out the job before giving the quote. I use a checklist to remind me of all the things I need to look for when giving a estimate, and if the windows are on the 3rd floor I assume the worse(unless its a newer home with siding). I also only give my customer the grand total for inside/out or for outside only. They don’t see my detailed estimate that will show I charged them for a scraping on those upper windows because I can’t see.
When I give them the estimate and schedule, they sign an agreement for that price, a precondition waiver and a scratched glass waiver all on the same estimate sheet. I have never had to ask for more money.
You need to buy your guys lunch one day for a job well done, they are truly customer friendly. I will also respond to that customer in form of a letter explaining that they were following your company policy. Let that customer know that they went above your standard service just to keep him happy. Explain to him that the reason you charge extra is to keep your prices low and only charge for the scraping service for those that need it. Maybe he will change his tune and realize he got something for free.