Parent a jerk or am I to sensitive?

[kindertime]

My contract states if they leave within the trial period I must give back unused fees, since she paid for all of August I don't want to risk them leave immediately, then I have to give the money back for days unused.

She paid for all of August? Not September? Well, today is the 27th, there are only 2 more days in August, (unless you work weekends.) You could make the last day Monday, the 31st. No?