All insurances are different..that's the first problem. I can tell you what I did with mine. I live in Tennessee and have Principal Financial insurance through my job. My child's doctor and her staff are a huge resource to me. Most physicians who specialize in vascular malformations are used to having insurances deny based on the "cosmetic" issue. First, the physician wrote a letter of medical necessity to my insurance company. I never saw the actual letter, but I'm sure it was full of all the medical reasons why PWS should be treated. The insurance company requested pictures, which I provided. That's all it took to get coverage for my daughter. As you probably know, I'm fighting an in network, out of network battle as opposed to them not wanting to cover treatment at all. I hate that for you. Do you have a physician yet? Maybe you could get them to help you. If they have sent a letter of medical necessity and you are still getting denied, just call your insurance company and ask them their appeal process. My insurance has a first mandatory appeal that a claim specialist (a nurse at my company) reviews. Then if that's denied there is a second voluntary appeal process (that a third party reviews). Like I said, all insurances are different so you might just want to call yours and ask them directly. Hope this helps!
P.S. What is this "msn account"? Are you referring to the sample letters the other posted message talks about?