Insurance company says it's not going to pay for chemo treatment for my dad...?

My father got a letter in the mail from his insurance company that they are not going pay for his in-patient chemotherapy treatment he received last week. According to the letter, the treatment was deemed "unnecessary." He received in patient chemo treatment for 5 days and had to stay in the hospital.
Who should he call first? It seems like the hospital didn't forward his referrals or records to the insurance company. My father received this treatment three times before earlier this year and it wasn't a problem. All of a sudden the insurance company is refusing to pay for his treatment???

You also need to find out if he needed to call for preauthorization before the treatment was given. Usually any hospitalization that isn't due to an emergency needs to be preauthorized.

i hate insurance companies. they usually have horrible record keeping, and when they mess up, its YOUR fault and not theirs... i've had claims being denied from cigna for the past cpl months... but because they claim ive never given them my social.. when i have, 5 times, and previous claims were processed no problem...

you gotta call up the insurance and ask them why specifically its being denied, and what paperwork they need to process the claims, then go from there.

First, he calls the insurance company to find out why chemotherapy is unnecessary. Maybe he doesn't have cancer? Maybe it was a clerical error.

appeal it. contact the insurance company immediate and ask why they didn't cover it.