I returned their call and a male with an Indian accent answered the phone. The line was very choppy and the guy keep asking me why I have to speak so fast and told me that I have to slow down. He said he is from IRS and I should know why he is calling me. I asked him if he is from the Internal Revenue Service of the United States of America, and then he hang up the phone after a brief silence.
Called them back repeatedly, gave them false names and addresses, they gave me the same bs each time until I told them there was no such person and cursed them and their family with 1000 painful deaths. They have now blocked my number, don't think they will be calling again. Don't know of any other way to make them stop , but it was very amusing messing with them.