Insurance paid wrong provider; correct provider now billing me
In February 2023, I got a PET scan. I received an EOB but didn't save it, so I don't know what it stated.
Didn't get a bill from the provider until January 2025 (so nearly 2 years after the service). They also sent me an e-mail saying "Evicore is responsible for processing our claims for Cigna. Evicore has recently informed jour office that another provider was paid for services our offices had rendered to you and is unable to provide us with any information."
I called up Cigna, and they weren't helpful. I had switched insurance companies in 2024 and the EOB was no longer available on their website either by that point. I just forgot about it and didn't hear from the provider for months. They then sent follow-ups in June and october of last year basically repeating themselves. I ignored it since it seemed like they should go after Evicore or Cigna to get it corrected.
Fast forward to this week and I get contacted by a collections agency about the bill. They insist it's ultimately my responsibility even though the error wasn't made by me.
Any suggestions on how to contest this?