I was I a similar position as you, and sometimes credit bureaus might be difficult to deal with, especially when high amounts of money are involved.
To make the long story short, someone opened a store credit card under my name and made a charge of around 3k. After reporting this to the bureaus, they did not want to remove the account from my credit report citing that the claim was "frivolous". After filing a police report, the police officer gave me the phone number for the fraud department of this store credit card, and after they investigated, they removed the account from my credit.
I would suggest to do the following:
- Go and talk directly with the hospital / organization / business where the medical bill was created. If you do not know the information of this organization, you can either look into your credit report, and see the original creditor name on the collection entry, or you can contact the collection agency, and they are in the obligation to provide information regarding who is the organization that send the account to collection. See the "Communicating with Creditors and Debt Collectors" section on this link. This section says:
Communicating with Creditors and Debt Collectors
You have the right to:
Stop creditors and debt collectors from
reporting fraudulent accounts. After you give them a copy of a valid
identity theft report, they may not report fraudulent accounts to the
credit reporting companies. Get copies of documents related to the
theft of your identity, like transaction records or applications for
new accounts. Write to the company that has the documents, and include
a copy of your identity theft report. You also can tell the company to
give the documents to a specific law enforcement agency. Stop a debt
collector from contacting you. In most cases, debt collectors must
stop contacting you after you send them a letter telling them to stop.
Get written information from a debt collector about a debt, including
the name of the creditor and the amount you supposedly owe. If a debt
collector contacts you about a debt, request this information in
writing.
- If after dealing with the hospital / organization / business, they still decide to not remove the collection from your report, then the last resort is to sue them, but this will involve costly attorney fees.
I know that you said that the main problem was that your credit account was combined with another. But there might be a chance that identity theft was involved. If this is the case, and you can prove it, then you might have access to more tools to help you. For example, you can file a report with the FTC, and along with a police report, this can be a powerful tool in stopping these charges. Feel free to go to the identitytheft.gov website for more information.