Is $13,000 to replace roof on house a fair price?

I signed a contingency agreement in March to pay out the insurance claim approval. The roofer later said the initial $12,000 from insurance wasn't enough, so I agreed to a $13,000 contract for just the house (excluding the garage), paying $1,000 out of pocket in addition to the $12,000 insurance check. The contract explicitly included flashing and metal drip edge. Two months after the work was completed and paid for, I received a random check and email from my insurance. The roofer had made a supplemental request without my knowledge or a signed assignment of benefits. He requested payment for several items, some already done and some not (like gutters and an extra dumpster). Insurance only approved flashing and metal drip edge, which were already included in my signed contract. I don't believe the roofer is owed this supplemental money because these items were part of the original contract, and he made the claim without my authorization or communication. My insurance adjusters and an attorney have confirmed that since I paid the contract in full, this supplemental money is mine. The roofer's contract also stated that any extra costs require written orders, which I never provided. I'm trying to understand both sides but haven't received a logical explanation from the roofer.