Hi,
Unfortunately in our line of work we get to meet all kinds of people,and not all of them are respectful and polite.After many years of doing this I am still learning...
That is why you need to set the rules and not let anybody bend them because this is your business and they are your clients.
I always ask for the payment in advance, after some time I know who I can trust even if they are late for few days with payment, but still send them a friendly reminder to pay. I personally would not go to court for only few days of not making payment, after all the child was not even in day care for those days and care was not provided..
What I would do is to learn something from this situation and next time do differently so this does not happen.
I had a similar lady who was constantly trying to “befriend “ me so she could bend the rules in many ways,I had to terminate it after two years of providing the service ,could not stand it any more..