You are generally responsible to ensure your medical bills are covered but here your issue is not having insurance but actually a couple of things. First, your medical provider should have submitted the claim in time. Talk to your medical provider and explain they are responsible for taking care of this with the insurance company and inform the insurance company you will have a claim against them and file a complaint with your state insurance agency if they do not show good faith and cover you. Explain it is not your fault your medical provider failed to provide the claim in a timely fashion. You could not have provided the claim and therefore explain to the insurance company that you are not to be held responsible and this is a matter that it must resolve with your medical provider. Call the medical board and file a claim against those doctors, as well and your attorney general for the business itself. Essentially, call and write to as many government agencies as possible to help you in this endeavor.