Anthem is having a hard time finding me in their records since changing my policy a little over a year ago

I have an outstanding emergency room bill for about $50,000 from when I was in the hospital on New Year’s Eve 2021, New Year’s day 2022, and the day after, January 2-2022. Prior to my lite stint in the ER, I had an HMO plan with Anthem, however, as of January 1, 2022, that plan changed to a PPO plan (still with Anthem). While I knew at the time that was going to confuse the living sh\*% out of everyone (which, of course it did), the hospital sent me a bill in the mail and provided me with instructions on how to go about proving the correct documentation to show that I did, in fact, have health insurance by uploading the required documentation.

Skip to 21/2 years later, the cliam was never resolved (oops, my bad), and it has now gone to collections, thus bringing my credit score down. While I have tried to get ahold of Anthem Customer Service several times, only to essentially be told they have no idea who am I, nor how to go about getting me in touch with someone who might be able to find me (as my member ID #, DOB, nor SSN seem to be of any help). I am starting to feel a little lost when it comes to getting this issue resolved. All I feel like I have to do is upload my membership ID card that shows the date that the new plan went into effect (1/1/22), to provide proof that I did, in fact, have Anthem health insurance before, during, and after my little new’s years day ER stay.

Has anyone else experienced this type of treatment from Anthem as a previously insured customer? Who has been treated like they might as well dropped off the face of the earth since they ended their coverage? Suggestions regarding a different approach/avenue I might be able to try would be extremely welcome. I’m starting to feel myself on the verge of bithcing out the next unsuspecting Anthem Customer Service Rep who picks up the phone.