In February 2015 I got an allergy test since I've struggled with allergies all my life but hadn't been tested in 20 years. Before going I confirmed with my insurance company that the test was covered. Fast forward to March 2017. Got a bill in the mail for $484 for this procedure, dated February 2015. WTF? This was years ago and I'm not even on this insurance anymore. Gave them a call and they literally said "We went through our records and changed our mind on that procedure - you weren't fully covered." I was out of the country for the first few months of the year so by the time I returned the "late" bill had already been sent to a collections agency since they or the hospital's billing department had never even bothered to call me. Not only that, but the amount the insurance company is charging is outrageous:

• Pulmonary Function Spirometry Test CPT 94010: $234 - national average is $36
• Percutaneous Test CPT 95004 x33 pricks: $660 - national average is $6 per prick and they're charging $20 per prick.

I've told the collections agency I'm disputing the bill with my insurance company which means they don't move forward with it for a few months, so now I have to call Aetna back and formally dispute the charges. What's the best way to do this? I feel like having a paper trail with my arguments is best, but doing this via mail will probably extend the process too long. Do I just call and complain and hope they lower it? And do I take the strategy of "it's unfair you changed my plan years later" or "your costs are astronomically above average"?