I can see her point, it does have an air of " I can't be arsed now I'm doing well and have better paid jobs".
( I maybe wrong perhaps there are other reasons)
Lesson learnt, some customers show loyalty and that should be returned or atleast be straight up enough to explain the situation to them. most would feel the same I think, a stranger comes to the door and says" I'm cleaning your windows from now on because Dave said it was ok "