Bought a bed 6 months back and now is tearing

I bought a bed July this year from Sleep Master and two weeks back when I making up my bed, I saw a large tear on the side of the mattress. It appears to be growing, when I called Sleep Masters, the person who is supposed to resolve my query called and I sent him pictures of the tear using whatsapps. He then asked how this tear occurred and I told him I would not know, maybe it is a factory default. He then told me he has been making this beds for years and he has never seen this happen and that he would not replace the bed. I told him I have been sleeping on beds for 29 years and I have never seen those bed do this. He did not even want to check for possible causes of this failure.