Unfortunately, you may not have much recourse in this situation. When you sign an agreement for medical treatment, you are committing to pay the full cost of the services provided; if your insurance refuses to pay the bill for whatever reason, you are responsible to the provider in full. If you think that your insurance should have paid the bill, that is really between you and your insurance company; you will likely be expected to pay for the service and then seek reimbursement from the insurer if the service was covered by your policy.
Although we have all become accustomed to the idea of having our insurance pay our doctors directly, providers bill your insurance as a convenience to you and to increase the likelihood that they will be paid. Ultimately, you are responsible for the cost of the services provided, and if your insurance will not pay, you are probably on the hook. While I understand that the provider told you that Cigna would pay this bill, the contract you signed for treatment almost certainly places the onus for paying the bill on you.
If you do not want this debt to end up in collections, which could potentially damage your credit rating, among other negative effects, you may be forced to pay the account yourself; you can then file a claim with Cigna if you think that it should have paid for this treatment. You may find yourself fighting an uphill battle, especially with the age of this claim, but I think that the insurer, not the medical provider, is where you should be focusing your efforts to resolve this debt.
If Cigna is unwilling to pay the claim, you may want to consult with an experienced insurance attorney to determine if you have grounds to file legal action against the insurer. However, you will need to consider that the cost of taking legal action to force Cigna to pay this debt will likely far exceed the original amount of the claim; it may make more financial sense to simply negotiate payment on the debt and take this incident as a lesson that you need to verify that any provider you use in the future is fully approved by your insurer.
I wish that I had better news for you, as I know that this situation is extremely frustrating. Unfortunately, you are likely responsible for paying the debt, and will probably need to do so if you do not want the account to lead to further collection efforts. I wish you the best of luck in resolving this dispute, and hope the information I have provided helps you make better money decisions.
I hope this information helps you Find. Learn & Save.