Not trying to sound self-serving, having represented clients for close to 40 years in this area, it is not advisable to attempt to manage the audit on your own especially in situations where the audit is not being performed by state employees. Over the last 30 years, the majority of these examinations are performed by third-party audit firms that are often paid on a contingency basis. The fact that auditors are being compensated on a performance basis can make the examination rather contentious. Consequently, retaining an advocate to represent your company’s interest is the preferred route to take.

To further compound matters, if your state of incorporation is Delaware, that fact will only make the examination that much more complicated and contentious in nature.

This does not sound like a tax question. If you were not notified by a tax agency I'm guessing that you got what is basically an advertisement by a company who searches state unclaimed property records and will tell you they found something for a percentage of what is there. These are public records that you can search on your own.