Phone support is not provided with the Free Edition. If you are using a paid version of the software or if you purchased PLUS you can get phone support when customer support is there. Otherwise, post your question here and someone will try to help.
To call TurboTax customer support
https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number
They are available from 5 a.m. to 9 p.m. Pacific time
https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number
https://twitter.com/TeamTurboTax
or
https://www.facebook.com/turbotax
Explain carefully what you did. It is not possible to e-file the same tax return twice. So-----did you file a federal income tax return using Credit Karma--or not? If you did and it was accepted, you are done. You cannot use TurboTax for the return. Or....if you e-filed here using TurboTax and that return was accepted, it would be equally impossible for you to e-file using Credit Karma.
Credit karma filled tax for me. And it got rejected By the irs.