Advice please

I live in Florida and starting a few months ago I started receiving bills for past services that should have been covered (and already paid) by my insurance through my husbands employer (these services, doctors appts and specialists, were from 2020 and 2021).I contacted the insurance company and they explained that they found out I had another insurance that was considered my primary insurance, so they took back all the claim money they’ve paid out (twice).The issue is that I have not had this other insurance for a year prior to the claims they are taking back. I had provided them this information at the time and have provided them a verification letter proving the date of termination. They continue to stall and say it is being taken care of and that all claims will be re-payed but I have been recieving bills in the thousands every day for months now and it is causing me severe anxiety and stress. I have talked to dozens of agents at the company about this. I don’t know what to do as the insurance company keeps giving me the run-around and I am afraid these doctors will send the bills to collection companies before the insurance actually does their job. The amount of stress this has given me has made me never want to go to another doctor or pay for health insurance ever again. Any advice?