I will bet anything you executed a settlement agreement without conferring with a lawyer, so now you are stuck with what you did. In some states there is a collateral rule which prevents private insurers from attaching liens on to accident settlements. In other states they can do it. Some medical providers are also allowed to attach liens pursuant to statutes in the state code. You need to find out if Humana is allowed to do it in your state. Do you know what the collateral rule is in VA? You need to find out. Also did Geico refuse to pay for medical treatment associated with your accident which was then performed by Humana? If you had had an attorney they would have been fighting to have GEICO pay these bills. You might have a defense in that you never got the bills, but if you knowingly accepted treatment that defense will be weak.
For many years Virginia law prohibited the introduction of collateral sources for payment of medical expenses in a litigation matter [ Burks v Webb, 199 Va 296, 99 SE 2d 629 (1957) ] but now that you have reviewed and signed the letter from Humana saying you agreed to pay hospital bills from the proceeds of the settlement amount you have a whole other type of situation. Whether the ruling from 1957 applies or is still accurate will take some legal research. I know this sounds like the Monday morning quarterback, but signing a legal document without the advise of counsel is never advised and is rarely a sound way to proceed. I agree with Mr. Sarno wholeheartedly in that regard.
You absolutely should consider to contact a lawyer. The questions you raise will require hours and hours of legal research along with a full understanding of many facts which your post does not address.
See if your local bar association can provide some suggestions, or check this website for Virginia lawyers that might be willing to take your case and establish an attorney client relationship with you.
Good luck and I hope this observation and Mr. Sarno's observations helps you some.
NOTE: This answer is made available by the lawyer for educational purposes only. By using or participating in this site you understand that there is no attorney client privilege between you and the attorney responding. This site should not be used as a substitute for competent legal advice from a licensed professional attorney in your state with whom you have an atttorney client relationship along with all the privileges that relationship provides. The law changes frequently and varies from jurisdiction to jurisdiction. The information and materials provided are general in nature, and may not apply to a specific factual or legal circumstance described in the question.
A roundup of the best tips and legal advice.