Tell her it`s costing her less in the long run- over a year say.
or , dont charge any extra !i dont charge any different between 4 and 8 weeks ( i dont do 12 ) , i dont advertise 8 weekly but will do it if they ask !
My work is run mostly on a 6 week cycle. Due to the winter we had I lost a complete cycle. Yet when I finally got round, most windows still looked clean. I had to touch the windows to feel the dust that was on them. It didn't take me any longer to clean them than if I had been on time. My point and question being: How much extra time does it take to clean windows that are done every 2 weeks compared to every 4 weeks?My answer is - none. I have a small number of fortnightly customers, so I am speaking from personal experience. Maybe some customers realise this. John.