I was billed for a procedure I did not have and now I’ve received a letter from collections

This was also posted on r/healthcare

Hi, I’m not sure how to proceed from where I am.

In March 2022, I had a OB/GYN visit, routine and was just a pap smear and a basic check up. My visit was completely preventative and should be 100% covered. A while later, I am billed for “surgery” but I did not have surgery. I contact the billing department at the clinic using a message system, to tell them that this is wrong. The clinic told me to reach out to my insurance company to get it reclaimed…I call my insurance company (I’m with Aetna) and Aetna tells me that we can contact the clinic and resolve this. The clinic did not answer in the call that was made, so Aetna recommended to file an appeal. I do that and Aetna tells me, while I have filed an appeal and await for the decision, the bill cannot go to collections. I receive the decision and Aetna “stands by their initial decision” and the letter says if I do not agree with this, I can submit a final appeal by writing to them. I write to them and I wait for another decision. Today, I revived in the mail my decision AND a letter from collections. The decision Aetna made, was again “stands by the initial decision” and that this is the final appeal. I don’t know what to do. I did not have surgery. I also have screenshots of the message with the clinic stating that I did not have surgery…so the clinic even confirms that I didn’t have surgery, and I am sure I didn’t have surgery (I think I would know…). I still don’t know what to do with the collections letter. What can I do now? Thank you in advance.