Have you tried to go online and verify? I am in a similar situation but I have to go in to the office to verify and they have locked the doors, turned off the phones and ran away. I can show u my letter if u like. It just says different ways to verify your identity.

We can help you with your IRS letter

You've received a notice from the IRS, and you're not sure what to do. We've got you covered.

https://support.turbotax.intuit.com/irs-notice/audit-support/