Insurance is really complex. First thing you need to know is who has the financial responsibility. Is it your company or the insurance company. If the company is just using the insurance company as a payor/administrator, you need to approach your companies human resources and discuss the situation with them, they can and in most cases will make exceptions.
If your company has purchased the plan from an insurance company, my suggestion is to bypass all customer service and go directly to the Office of the President of the insurance company. THey have a staff there that I think is better equiped to help than customer service.
Go onto the internet and search for the insurance companies corporate number and when you get the operator ask for the Office of the President. Do not be afraid to voice your concerns. I would do this first even if you get a denial, before you go through the ERISA Appeals Process. I have never had to file an appeal yet, have come close but have gotten everything taken care of before that was necessary through this office with three insurance companies.
Do make sure that your request is not unreasonable, and always document all of your conversations, so that you have good information behind you. I was on Mepron/Zith for a total of 12 months, 2 6 month periods, and I never had a problem getting it paid for.
If you can not get satisfaction from the Pharmacy plan they are normally subcontractors to the insurance company so go up the ladder there too. You will never get the number from customer service, that is why you have to find the corporate number out yourself. Good Luck.