I got a call from these idiots. First report them to the IRS and the FTC, then harass them back. I've personally shut down four of their numbers temporarily. If we can multiply that by 10 people calling and harassing them, their lives are going be so miserable they won't know what to do.
Their numbers also include 6097; 6098; and 6099.
Block your caller ID from being shown, then call and don't say anything. Keep repeating this. If they have to answer calls like that they have no time to scam other people. Plus it's a lot of fun.