good going only one drop out since then these are the reasons why most drop out, what ever happens dont loose sleep over it ;p,
i would write back maybe, show her a few URLs about the reach and wash ask her to investigate wfp and you will call her when she has had a chance to.
End of the day if she wants her windows cleaned thats what you do.
i had one the other day windows wet , so i went with her to every single window they were all spotless, we wacthed them dry in the sun, we even saw a bit of water run down from the mid frame to the bottem window i poionted out there is a small chance cos its a first clean that might bead a little but i rinced well so i dont think it will , oh look its dryed clear too, are you happy? she still said hmmmmmm kind of happy, i dont know ,,, thou,,, hmmmmmm
why do they want us to risk our lifes and damage guttering and roof tiles? she said she would be much happer if i was up a ladder

i said if i ever dared ladder this house it would be double for the same result so i think she might stick but who knows,who cares a day in the life of wfp!