I would take them back but under some serious conditions, such as paying on mondays for the 2 weeks coming. I would require post dated checks for a few months.
And of course, a deposit worth od 2 weeks of care would be required.
But you mention some facts about the kids being spoiled. That is not something we can really help you with as you are the only one that knows if you can put up with it! Money wise, you can ask for payment in advance so it is pretty simple to solve, but if its a question of the kids bein spoiled... you have t think about it!