Because it was a round we bought and that is what she's used to from previous window cleaner. Pain in the bum. We don't offer that to any we canvas unless it's impossible to get round the back which it isn't with this one
Is this the round you bought a couple of years ago? Has she always been in on previous cleans?
There are 2 sides to this though.
Whoever you purchased the round off did they explain all the customers requirements to you? Did you ask them for a complete run down of the ones that want just that little bit extra?
Yes it is annoying that she wants a service that is not in your criteria, but it is only what she is used to with the previous cleaner. When you took over did you explain that unless it is for access reasons you don't make calls prior to the cleans. This would have broached the subject with her and you could possibly have come to an amicable agreement over it, or not

Ok so she only wants cleans when she is in....... how many others do you have close to hers? (same street, next door etc etc) How long does it take you to ring the door bell to see if she is there or not....30 secs to one minute? So if she is in you earn money, if not you just go on to the next one. ;