Customer not collecting deposit after lay bye transaction is cancelled

A customer makes a Lay Bye and the owner makes a condition of Lay Bye 3 months to Pay and No Refund and No Exchange and the customer signs to this condition. Sometimes the customer does not collect the Lay Bye and the owner cancels the Lay Bye and resells the item and if the customer comes back she gets a full refund of deposit paid but sometimes the customer does not collect her deposit,
Also to note the customer Lay byes an item in winter and now the same item in summer we have to sell at a Lower price. The customer that does not come back to collect her deposit what is the shariah ruling just to mention she signed the condition after 3 months no refund or exchange.