Recovery Rebate Credit

I filed my taxes using TurboTax.  I had a child born in November of 2020.  The software reflected $500 for this child for the EIP 1 and $600 for this child for the EIP2.  The IRS amended my return citing a math error.  They are telling me I am not entitled to the Recovery Rebate Credit due to his date of birth in November.  I called them.  Now they are telling me I am not entitled to the EIP1, but I am entitled to EIP2 to send them a letter in response to their bill.  Thoughts?