Is it a technicality?

My house with three bedrooms and two bathrooms located in Connecticut went into escrow that was supposed to last 60 days. Nevertheless, one week before the closing I was notified by the real estate agent that the house did not apprise for the amount agreed upon in the sales contract. The buyers are refusing to obtain another mortgage company or another appraisal at my cost. What will happen now? Do they forfeit their $2500, which is in escrow to me? Is it a technicality? Do they get their money back?