Second hands Parts

Good day..I have a problem with that insurance I have a recent claim with them my car was burned on the 26 it’s being a full month they have my car,they send me email saying my car it’s a write off next thing the call and saying they gonna fix the car ,now people who supposed to fix my car called around last week saying they ordered parts for my car,now they telling me they need my authorization so they can fix my car with second hands parts then I refused they said it’s an order from my insurance they authorized for second hands parts.Yesterday Miway called I asked them about it they said they did that because my car is not on warranty anymore but I was never told that thing about warranty they said it’s a “common “thing..I have being paying for 7years and they never said anything about warranty if I knew about it I’m sure I wud have went to other insurances,what if in a long run I have a problem with same things what then..HELLOPETER YOUR HELP WILL NE HIGHLY APPRECIATED