I filed my 2018 taxes through turbo tax and turbotax has failed to ensure I get my money back. How do I get my 2018 tax return? Who do I talk to.

Your 2018 Refund?  Did you call the IRS?  What did they say?  If the IRS changed your return they would have mailed you a letter explaining.

Was your return Accepted?  When you efile you get back 2 emails.  The first email only confirms the transmission.  The second email says if the IRS (or state) Accepted or Rejected your efile. Just paying the fee doesn't file the return.  After you paid did you continue on to the very end and hit the big orange Transmit Returns Now button?

Maybe you didn't finish filing it or it Rejected.  When you log into your account you should also see the status and if it was Accepted or Rejected, Started, Printed, Ready to Mail, etc.  what does it say?