Bad experience

I bought pvc blinds, and within a month 2 of them torn in the middle. I have send the pictures and ask for a credit for some other blind as I did not want the same again. His reply was that they dont recommend the PVC blinds as this is bad quality. He contacted the manager who refuses to give credit as I dont have the packaging anymore. The blinds are on the wall and lasted a month... who would keep the packaging, seriously. I said I will take if off and bring to them... you cannot sell them again....If it is sych bad quality, why do you stock them? And why dont you tell me before hand?