Staying beyond 240 days while H1B extension is pending

[tam90]

Currently I am employed with a company and below are my details:
1. I-94/Visa is expired on April 7th 2017.
2. My company applied H1B extension and case received by USCIS on April 5th 2017 and received a receipt.
3. As case is still showing pending, so my company applied premium processing and case received on November 8th 2017. I received a NEW receipt Number and it is not same as original H1B application. When I checked status using the new receipt number, I see RFE request on November 14th 2017.

My question: What would be legal status as case is pending and nearing to 240 days (on December 3rd, 2017), can I stay in USA or do I need to leave immediately after December 3rd, 2017? What is the impact on my employee relationship with my company?
Also, is it correct to have 2 different receipt numbers for one case (one for original and other for premium processing upgrade)

Thanks.
Tri

[newacct]

You can stay in the US for as long as a timely-filed extension of status is pending. But you will not be able to work past 240 days after your status expired.