Faulty iPhone 12pro

I bought a refurbished iPhone 12pro in November 2026 and when I received it I just switched it one to see if it working and I never put in the Sim card since the person I bought for was hospitalized. On the 1st of June when we try to put in the Sim card the phone doesn't have network. I tried to contact them they tell me it's out of warranty. But truth is they sold me a phone that is not working meaning I lost R9k. I asked them to atleast have it checked out and fix it I'm still willing to take it back but as long as its working