Refusing to repair phone in warrenty

I took my Samsung S7 Edge to be repaired under warranty to TT3 Repairs in Port Elizabeth. It was within the 2 years and I had the original purchase invoice, The issue with the phone was a vertical pink line on the screen. A quick internet search of "S7 edge pink line" revealed it was a common issue with my model phone. The shop assistant took my phone to the back for a technician to inspect. The assistant returned and told me that my phone had "physical damage" and therefore my warranty was suspended until it was fixed and I needed to pay R4,200 to replace the screen. The "Physical damage" to which she was referring was minor scuff marks on the corners of the side frame of the phone. Other than the pink line the screen was immaculate with damage whastsoever. I stated that it was obvious that the side frame marks were not the cause of the pink line. The asistant agreed with me but stated that because there was physical damage despite being completely unrelated, the warrenty was not valid and I needed to pay for the screen replacement myself. I refused and said I would take it up with Samsung directly. The assistant unsympathetically said that, "It was fine because Samsung would tell me the same thing". I did as I said and contacted Samsung. They advised me to go to their own Samsung repair facility. Samsung repaired the phone under warranty without any fuss and without even one mention of physical damage! This is what I would expect from a genuine warranty repair. 5 stars to Samsung! Zero to TT3!