Refusal to repair phone even under warranty

Took my phone in for repairs, as the phone, S8+ switched off and refused to turn back on, took the phone to MTN, they advised i need to take it in directly to Samsung, i took it to Samsung, keep in mind the phone is about 18 months old, Samsung says they cant repair the phone as it is out of warranty as they is a really really small crack at the back of the phone, which is made of glass, so they say they are going to quote me to repair the phone, and they are going to charge R180 for the quote, this is really disappointing, customer service pathetic, will never ever get another Samsung phone again