I would say be as nasty as you have to be.
Say that you filed the paperwork as required by them so they have no reason to deny it. I might even suggest you say that you are sliding backward without the necessary medicine and you might have to go to the ER if it isn't filled immediately. When in doubt ask for a supervisor, you will be on hold for awhile, when that doesn't work keep going up the chain. Threat legal action if you have to.
I'm so sorry you are going through this. :(
**Edit** Alright so I looked into it a little bit. An insurance company Can NOT DENY MEDICATION IF IT IS PRESCRIBED** They can substitute with a generic alternative at their discretion but regardless I would call right now, go above the chain of command, disregard the 48 hr notice especially since it has been longer, tell them you don't care about the 48 hrs because your meds have lapsed and it could be putting your health in danger etc. etc.
Let the insurance company know that if you don't have the prescription filled/approval paid for this afternoon that you will report them to the Department of Labor’s Occupational Safety and Health Administration. Bluff if you have to, tell them you have the phone number and you are ready to call.
What Do I Do if My Employer or Insurance Company is Not Following the ACA?
The Affordable Care Act contains many requirements for insurance companies and employers.
If your employer or insurance company is not following the ACA, you can report them to the Department of Labor’s Occupational Safety and Health Administration. A fact sheet explaining how to report ACA violations can be found here: http://www.osha.gov/Publications/whistleblower/OSHAFS-3641.pdf
The ACA protects people who report violations. This is called whistleblower protections. This means that insurance companies and employers cannot stop a person’s health insurance, fire a person, or retaliate against people who report violations.
To view the Department of Labor’s interim rule about reporting violations, go to: http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=FEDERAL_REGISTER&p_id=23585