Samsung S7 edge - Warranty void due to scratch

Please can someone at Samsung help????

The main board on my Galaxy S7 edge went the other day. I am sure the phone is under warranty still but am told that due to a very small scratch on the corner, that is over a year old, my warranty is void and I must pay roughly R5k to fix it.

I have had the phone in a cover for the last year, so this scratch is a year old and cannot understand how this voids my warranty? Apparently any physical damage results in your warranty being void. Does this mean that if I have a scratch on the screen and my mic stops working is the warranty void.

Please can someone get back to me regarding this asap. I use my phone for work and this is beginning to effect my life!

Regards, Damian