@momof5
I like nschildcare approach. Her post gives specific advice on how to take action in this instance and then obviously you need to work on preventing these kinds of issues from occurring again in the future.

You won't be being a bitch so don't concern yourself with that worry. Let them know quite clearly and to the point that upon their request to extend care hours for their convenience, you did so at no additional charge as a FAVOUR! Now they are taking advantage of this by going home to shower and change amongst other things prior to pick up which is not a necessity, requiring longer daycare hours and that pick up is even later than the agreed time. Let them know as a result of their actions, their pick up time is to be moved back to the original contracted pick up time of 4:30 and should late pick up after this time occur, a late pick up fee will be charged per minute and they run the risk of termination of contract. Personally, all though I know others probably wont agree, I would give them one chance of being late, just to prove to them you mean business when you remind them that care is suspended until late fees are paid, and hopefully that will turn things full circle and they will start respecting your rules again. Failing that, if it occurs again, give them written notice! Some people need to be worked with rather than the go to response to difficult situations being to always terminate. They are abusing your rules because you allow them to, so you need to get that in check. Now if it was behaviours that you had no control over then sure, you would be fighting a losing battle, but in this case I think it's worth one last ditch effort to salvage this relationship if you can.