Funny/Not So Funny Letter From My Insurance Company

You may remember that I need to get a BRCA test, a genetic test that will determine if I have either the BRCA 1 or BRCA 2 genetic mutation. A positive result would mean my changes of getting cervical cancer, uterine cancer, or a recurrance of BC are high.
The test costs $3,000.
So, a few months ago, I called my insurance company to see if they'd cover it. Yes, they said, but we need a letter of medical necessity from your doctor.
I called my onc a few times and left messages telling him he needed to write the letter. No response, of course, so at my next appointment, he said, "'Ave you 'ad ze BRCA test yet?"
No, quoth I, have you written the letter of medical necessity yet?
He looked confused. Of course, the man goes thru nurses like nobody's business. I think he's on his 6th one since I started going there in February of '07. So, he scrawls a letter on some letterhead, and hands it to me. I fax it to the insurance company.
I get a CC of a letter sent to Dr. Casimir. The insurance company couldn't read his writing (surprise!), so they sent their response to the 1st doctor listed on the letterhead. I called Dr. Gressot's nurse, who talked to Dr. Casimir's nurse, who of course had no idea what letter she was talking about.
I call the insurance company again, and have them re-send the letter to Dr. Gressot.
Then, two days ago, I get this letter from the insurance company, edited to avoid boredom:

We have completed our review of your request for coverage of BRCA test. Based on the information reviewed, we are pleased to inform you that coverage is available. All covered services are subject to screening for allowable charges. The final allowable charges will be determined when the bill is submitted and will be based on the actual services provided. Please note this letter does not guarantee payment. Benefit payment is based on the provisions of your benefit plan.

Huh?