What?? No one warranties strings. What nonsenseIf they have what you want to use in stock, you should buy your strings from them. If they do not stock them, you should ask if you can supply your own strings. If they are okay with that, under no circumstances should you expect them to warranty strings you purchased elsewhere. If they say then can special order your strings, but will not warranty them in any way, RUN as far and as fast as you can! That's part of the risk they assume using strings that they sell.