What all have you done in response to the 5071c letters to verify your identity? Did you try verifying online or by phone?
Have you phoned to speak to the IRS?
Have you spoken with the IRS Taxpayer Advocate Service?
Is there an IRS local office in your city or nearby? If so, you can make an appointment. You can look up the locations with the tool at this IRS site:
https://www.irs.gov/help/contact-your-local-irs-office
See this IRS page about verifying identity. It outlines several ways to verify
https://www.irs.gov/identity-theft-fraud-scams/identity-and-tax-return-verification-service