OT Lawyers (and Doctors, to a degree)

My 19 year-old son was in a car accident six months ago and had to be airlifted by helicopter to a nearby hospital. About a month after the accident we got a bill for over $46,000 from the company that provided the helicopter service. We were shocked, to say the least. I immediately called and gave them my insurance information and asked them to file. About a month later, I received a letter from the company saying that my insurance company had denied coverage, and they included a grievance/appeal letter that they asked my son to sign and return so that they could send it to my insurance company. We sent it back signed. About a month after that, we got a notice from the insurance company that they had paid over $7000 on the claim. The next day, we received another form letter from the company that they want to send to the insurance company saying that the payment that they received is unacceptable and that we are certainly not able to afford to pay off the balance. They also sent a HIPPA release form for my son to sign, giving them permission to access his medical records. I am pretty apprehensive about pushing this, especially giving them a HIPPA release. Am I right or should I allow them to continue the appeal for more money from my insurance company?

ETA: I don't see any reason for the helicopter company to need access to my son's medical records.