H1 denied and OPT extension deadline Nov 9th

[sat.23]

Hi..I am in a critical situation now. My H1B got denied today and initial 12 month OPT period ended in July. In May I have applied for STEM extension with Cap-Gap I20 (from July to Sept 30) that was provided by university. So I got an RFE from USCIS asking for proper STEM I20. The deadline to submit is Nov 9. If I get STEM I20 by then and send, all is good. If by any chance, I didn't send by Nov 9th, what are the options I have? Not aware if sending an email to USICS/visiting a local field office explaining my situation and asking to extend the date would work??
I heard about the 60 day grace period. Would 60 day period count from July or Oct 1st.
Please do help me