Guys finally worked for me also. Though I already raised service request through other category earlier but it didn't worked for me. What worked actually was going to Jio center in lucknow second time talking straightaway to the manager(other middle level officers were just saying rubbish) He noted my prob, number, alternate no. Then referred me to an executive at nearby desk. He examined my Jiofi n noted, IMEI, Mac address, RSN e.t.c. then sent all info to someone through his Jio employees system in front of me. He checked n said "sir apne to sari hade'n to paar kar di complaints ki..." (I filed total 10 complaints through service requests since 28th August).
Then he told me, ek call ayegi alternate no. Pe to confirm ki issue solved ho Gaya in 24-48hrs.
Got msg of welcome offer activation in 36 hrs n everything is working now.
They seem to call this something like CSD or CST or (something sounding like that )activate ni tha apke mein... so I think u all know what u have to do...
Remember: EVERYONE IN JIO OFFICE THINK HE HAS DOUBLE PhD IN JIO'S PROB, even guard said "Saar sare aap fir se install Karo, reset Kari, fir service Kari, Abi karo n all bullshit. Just don't listen that. Acc. To manager, Jiofi has nothing to do with app installation. Enjoy