Personally I'd be super concerned about a parent who feels they can simply negotiate your policies and fees.

What gives her the impression that you would be willing switch or change things up just to make it work better for her? Why wouldn't she assume that the fees you charge and the way you have your payments set up wouldn't be in YOUR best interest and that is why you do things the way you do.

I set my rules and policies and they are NOT negotiable.

I'm sorry but I see this as a MAJOR red flag and would not entertain the idea of getting together to discuss any of it with her.