On the detail: this is a paperwork problem with a paperwork solution, and framing it that way is the most useful thing anyone can do.
The denial letter states a specific reason. The appeal should address that reason first and explicitly, with the missing evidence attached, rather than restating the original case.
Each criterion must be evidenced in the clinical record, dated, before the request. A criterion asserted in a covering letter but absent from the notes is the commonest reason for a denial.
Peer-to-peer review is a standard step in utilisation-management processes and resolves a meaningful share of disputes.
A prescriber has to submit the request; this is a description of what makes one succeed, not a substitute for one.
Evidence every criterion in the dated record, not in a covering letter.