Appealing the amount I was reiumbursed for an out-of-network service

Hi all,
I recently received reimbursement for an out-of-network service that is very low for the price of the service (it costs about $3000 and I was reimbursed $300). If possible I would like to appeal the amount I was reimbursed.

Here is the context:
The service is a highly specialized genetic test that is only performed at about 5 labs total in the country. All the labs charge about the same rate for the test $3000. To bill for the testing, the labs use the unlisted CPT code 81479 because there isn't a code specific enough for the actual test (it's a custom designed test based on one's individual DNA testing for a single gene).

I have Horizon BCBS (in NJ) but the plan is part of the national network. They denied the claim twice in the first place based on not having a detailed description of the service, but after submitting (and re-submitting) a description from the provider of the test they performed, they did approve it, but just for this low rate.
I don't know if this is relevant, but 2 years ago I had Aetna and the service was in-network and Aetna's in-network reiumbursement rate for the service was the full $3000 at that same lab. I mention this because I don't know if the "reasonable and customary" amount is something that's accepted across insurance companies. So apparently Aetna found the rate to be reasonable, but I don't know if that is something determined by individual companies

I wanted to get advice on what I should include in my letter of appeal to have the best chance of getting reimbursed at a higher rate. (Or if this is a losing battle altogether).

Thanks in advance for your help!

ETA: apologies for typo in the title 🫠

submitted by /u/Old_Perspective_6417
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