Customers like that make my day. If they take the time to ring I always try to go the extra mile for them.
Even if its just cleaning their kitchen window inside each time its worth it.
I picked up a lady who within 3 days of cleaning her windows, got me another £80 worth of monthly work by telling people how happy she was. Said her windows had never been so clean in the 30 years since her and her husband built the house.
I clean her inside kitchen window every time. She offers to pay, but I aint having it!