FOIA request doesn't returned I-797 for I-140

I requested for I-797 approval notice for I-140 via FOIA, not just once but twice. Both times I did not receive I-797 notice of I-140. One time I got I-140 petition with out an approved stamp other time with a stamp on the right side top corner.
I’ve been in conversation with FOIA Questions help desk thru email and when I asked why I did not receive the i-797 copy they replied that “The records retention policy changed in 2015 for the I-797 receipts/approval notice of I-140’s. They are no longer required to be maintained in the file”.
I need to file for my spouse H4 EAD and looks like i-797 of 140 is a required document. My employer is reluctant to share the approval notice rather he suggested to go thru the attorney to file H4 EAD and the attorney is charging heftily.
Is there anyone else in the same boat? How can I resolve this? Is there any specific way to receive i-797 from USCIS FOIA? or Can I just use the I140 approved petition for applying H4 EAD?

You can use the i140 document that you have received from FOIA to file H4 EAD.

The best option is to get the i797 from employer but if they are not sharing, then your next best option is to use whatever you have.