Several years ago, a friend who is a nationally published investigative journalist invited me to go along to his Atlanta interview of two female IRS whistleblowers.
Among serious allegations of MAJOR sexual harassment by male superiors who were routinely promoted to higher positions and/or transferred in order to display their genitals to NEW female subordinates we were told of the Dialing for Dollars program then and apparently STILL a routine practice.
This is the reason to never cooperate with the IRS. Unless you owe them a great deal of money, an agent can reach his dollar quota by going after those tax payers who are more compliant.
Just ignore their letters, and they go away. Until you are personally served with court papers, it's just negotiating and that does not mean you have to talk to them.