DON'T GIVE UP! I fought it all for years before they (medicare) finally gave in! I say that you push the "I started my process before you changed your policy" line! If it's there policy to stick to the policy that was in place during the first line of paperwork, then they should abide by it.
Remember, if you think that this procedure is your last chance for change, you are worth all the work neccessary to get it. I went on and on fighting for 3+ years and I am so glad I did.
Angela