

Once you've read and you understand the reasons for denial, you now must think of how to explain your appeal clearly.
Note that the appeal letter doesn't go into great detail. That can come later. There is no anger expressed. This is a business letter and it's counterproductive to believe that you should tell them all that's on your mind.
You will soon receive a notice that your appeal is in process. Now you have to decide to DIY retain a lawyer to represent you.