If I text a customer about their gate needing to be unlocked and upon arriving, it's still locked, they get charged 75% ofthe price and yes they pay it. Alternatively if they let me know that they are away, I do what work I can and charge appropriately and again most are fine with this.
If I turn up and it's a good reason why I can't clean, ie having some external work done, then it will simply be skipped until the next visit with no options of me fitting it in the next day. Yet saying this, I have some very good customers, which I do allow to organise the work. So for instance in an area of my Campsall round, it takes me two days to complete. I will let her know which 2days they are and she will let me know her schedule ie tue morning is ideal before 12. I can work with that and like I said she is a very good customer. Now if she wasn't, I would not give her the option.
I also have a two strike rule.
So in your case, I would simply apologise that she feels that way and unfortunately I do not offer the service she is looking for and wish her the best in finding one which does.