Poor fitment caused cracks in 1 day

I just went to BSG AUTO GLASS Katlehong to replace my broken windscreen. Everything was fine up until I get home where the windscreen from the top went up. I didn't worry much as I wanted to go show them next morning. Come next day, the windscreen cracked on the bottom corner from driver side up to the mirror. I went to report this they examined the screen and the said I put pressure on it. I don't know how.