product damaged customers garment

I am a laundry owner in strand an purchased bleach powder from kleen chem. I used it to soak a customers garment and it came out shredded. I reported the incident and I'm told that the product isn't theirs. They suggest that I buy another shirt do that they can come test it in front of me. What's the point? I have to replace the customers damaged garment and they expect me to go out and buy for their testing! Which world do these people come from. I'm upset with the lack of accountability. How can it be so easy for them to make a sloppy excuse like that especially that the consultant acknowledge the fact that he sold me the product. I'm disappointed and surely will never buy anything from kleen chem. Your service is an embarrassment.