--precisely because there have been more problems reported with the statin drugs recently, and there's been a bit of a movement to switch people to Zetia. With that increased demand, there may be somewhat of a pinch on supply--and when an insurance company sees a profit opportunity . . .

I wonder if you could get a letter from your doctor--or you could write yourself to your insurer--explaining why you CANNOT switch to one of the statins, given your neurological situation. (After all, many of the bad side effects of statins involve muscle and nerve pain.) You should also explain the fixedness of your income, status, etc. You may be able to argue that it's in their interest to let you continue Zetia at the previous rate rather than risk probable future complications (that they would have to pay for).

(Nah, that's too logical an argument for an insurance company to follow . But it doesn't hurt to try.)