YRC Freight Chicago LOST 2/3 of our shipment! Chicago Illinois

My husband scheduled a shipment of 17 boxes from Colorado to Chicago. When the shipment arrived in Chicago, there were only 11 boxes. The driver said that was all he had been given and left. When we called the customer service number the lady called a few of the warehouses and then emailed us later saying that the 6 boxes were gone and they had no idea where they were. The company told us to file a claim but seems to have NO intent to find our boxes. These containers held my husband's personal possessions along with some of his deceased mother's belongings...we want our boxes!