I got my racket strung with NBG 98 at 26lbs, purchased from an online seller. When I used it for warmup practice, I notice a very weird sound. Its like a mix of guitar strings being plucked and nails on a chalkboard. It got louder during the match, and then the string snapped after barely 2 matches. Took it back to the stringer and he said it wasn't his fault, blaming that the string used was a CP type (not the usual SP or JP). He offered a cheaper string, but I refused and got the racket restrung with another stringer (same string, code and tension). It did not snap after 7-8 matches and sounds normal. Question - does the weird sound I heard indicates the string was badly strung, or the fault lies at the string quality itself?