Samsung A8 2018

My partner bought a Samsung A8 2018 cash on the 4th June 2018 at Samsung Sandton,now my screen is black .I went to Samsung store at mall of the north they told me that the phone maybe it was pressed to hard or it fell they say it has . My problem is that the phone screen have no scratch or even a crack but they say I bumped the phone, now they say the warranty won't cover I have to pay for repair . I bought the phone for R 8509.99 now I have to pay R2338.47 the phone is only 8weeks old.