If you have a written agreement over a disputed school refund signed by you and the representative for the school that you are writing about, then the agreement is the agreement. Legally the school cannot unilterally change what was agreed to in writing assuming you did not know there was a mistake in the calculations.If I were you, I would write the director a letter (keeping a copy for future need) advising that there has already been an agreement as to the refund paid you that was in dispute and that the written agreement signed by him controls the situation.Good luck.