Terrible service from parts division

My husband went to purchase a new part at the sales department. He was tod to bring in a sample which he did. The salesman searched according to the vin number and the part on the system did not match the part he had. Together with the salesman, they searched for the part closest to the one he had. He paid for the part to which they said they would order the part. When the part arrived, it did not match the old part and neither did it match the drawing from which they chose the part together. Now they are refusing to refund his money and neither are they willing to exchange it. The salesman who helped in not even willing to assist. Customer service is terrible