I strung a racquet for a client on the 20th of January. He had requested syn gut at 58 lbs. I strung the racquet with Babolat syn gut at 58 pounds. Three weeks later he dropped off the racquet to be restrung, claiming he didn't like how the string felt and wanted to try Xcel. I contacted the client and explained he would have to pay full price for the Xcel and stringing. He felt like he should only have to pay for the price difference in the strings for the upgrade. The quality of the string job was not in question, but rather the "feeling" of the strings. What would you guys do in this situation? The situation has already been resolved, but it would be interesting to hear what some of the other stringers do. Thanks!