How to Write a Letter to Appeal a Disputed Claim?

Hello,

I have never wrote an appeal letter to dispute a claim before and I wanted to know how to go about it.

Also, what kind of supported documentations can I attach with the letter to support my claim? Unfortunately, the only proof I have are the text messages, that were exchanged between me and the other party member that was involved in the accident, in which the other member admitted to rear ending my car.

Thanks.

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