How do I write this letter?

[poptart]

Where I live (BC, Canada) chest surgery is free to the patient and covered financially by the provincial health plan. I have to write a letter to the woman who works in the medical services branch and request reimbursement for it.

The endo who gave me her mailing address said I have to include that I am a "trans male" seeking reimbursement for top surgery, the names of my 2 doctors, and my social insurance number.

How would I word this exactly? I've never done this kind of thing before. And does it have to be all formal or can it be a few lines straight to the point? 

[Kreuzfidel]

I would keep it short and to the point.  As for formality, just be polite.

[poptart]

Well yeah, I wouldn't be rude and demanding. Haha. I mean I wonder if it has to be a formal business letter structure or if I can just write a few lines. Still haven't done it. No clue what to write.