Hi,
I have faced same issues, During vis interview They asked me to submit company tax docs, and handed over yellow slip.(note this slip colour )
I personally went to embassy with that docs and submitted. they took passport and tax letter, I797 original Approval notice.
After 3 days got call from them, stating they r returning my passports and need further admin process. recvd passport with pink slip.(pls make note of this slip colour)
10 months passed , no update, for my emails they respond Still under admin process.
Employer says no one contacted him, I left with No idea on what to do.
finally I sent an email to embassy and asked where my file is located, then I got wonderful reply.
Pls submit the documents mentioned on yellow slip. thats it my fuse gone.
I replied to their email all the story, along with the pink slip I was holding as an attachment.
they asked me re submit tax docs , and i submitted.
Just with in 4 hrs I got mail to drop my passports to issue visa.
In your case if it is going more delay, Pls make sure they have received the requested docs.
if they say not received then follow up, if they say received, then check where your file located. whether it is with embassy or returned to USCIS.
If returned to USCIS contact ur employer on what to do next.
Final Bump in my story, Embassy lost my I797 Original approval Letter, and tax docs, Now I have Visa but not 797 Letter , SO I applied for duplicate copy of 797. 