I received a notice from the IR s about earned income tax credit that I never filed for. It's been a couple of months now and they know nothing of it when I call them

Earned income credit is available for some single individuals who work low income jobs, and for individuals with children (married filing jointly or head of household) who have low-middle income jobs.  It's basically free money.

https://www.irs.gov/credits-deductions/individuals/earned-income-tax-credit-eitc

IRS computers send out letters if it looks like you might qualify but didn't claim it. Usually a CP27 notice. However, Turbotax will automatically claim EIC if you are eligible, unless you override that section (which is impossible online and difficult using the desktop software.) So if you filed with Turbotax and didn't claim the credit, odds are you aren't eligible.  If you used other software or filed manually, you might have missed it.   

If you got a CP27 notice, follow the instructions here to see if you really are eligible.  If you are eligible, you can file a form to get the credit paid to you without needing to file a whole amended tax return.

https://www.irs.gov/individuals/understanding-your-cp27-notice