I'm so sorry you're going through this. I wish I could order some, but I already have lots. I might order some for my sister's rescue. But I have to save money for our big move coming up.
As for your DC problem, lots of people get paid on the 1st and 15th. Too many people are irresponsible and spend their entire paycheck before then (even if they have prior obligations.) It looks like this is what happened to you. People are also figuring that it's not as important so their spending the money on other things instead. If you let them get away with this ONCE, then they will do it again and again! They might even be telling each other that you don't seem to care of they're late.
I would suggest either making it more serious with pentalties or if you are afraid to lose anyone, change the due date to the 1rst of the month when people are more likely to have their money and charge them extra when they're late on it. They need to take your business more seriously like they would their rent or car payments. I am sure you're a wonderful babysitter and you will find other kids, I know a good babysitter is hard to find. Good luck.