What to do if my insurance denied claim after I received care.

Hi, so not too long ago I was sent by my doctor to get an MRI done on my upper extremity to a radiology place. When I set my appointment online, I got a call the day before my appointment from the radiologist front desk to let me know my insurance denied it and need more time to gather information. They schedule me two weeks in advance and I didn’t get a call anymore. Two days before my appointment I get a message from the radiologist location to fill out information online and had an option to pay too. My payment was only 65$ for an mri, so I assumed they approved it because I paid for another MRI but for something unrelated about a year ago and that came out to a few hundred dollars. I paid the 65$ and when I showed up to the front desk on the day on my appointment they didn’t tell me anything. They just asked for insurance information, my personal information, and were reviewing some stuff. They confirmed I paid and I was good to go and I get my MRI done.

I check today on the Sydney Health (blue cross blue shield PPO) app on my claims and it said denied and that I owe 1.3k dollars for the care. What’s annoying is that another claim was denied too over physical therapy despite the location assuring me they got the approval. I went in, paid 11$ copay for the service and now the insurance wants me to pay 230. I’ve gotten care from these places before and never had denial or problems.

For the MRI it states:

“Your plan’s benefits don’t cover this kind of care.Your plan’s benefits booklet details what’s covered, but you can find answers online instead. Just visit the Benefits area for a searchable list. Information about all of your benefits is there, too, in one convenient document. It’s also the right place to get an appeal started.”

For Physical Therapy: “The member’s plan doesn’t cover this care. It doesn’t meet clinical guidelines for being medically necessary. The member is responsible for this amount. You can check what’s covered in your plan documents or on our website.”

What should I do exactly?

Call the insurance? Call the doctor? Call the radiology place? All of them?

This is in Nevada if that helps.

Any advice is welcomed, thank you.