i think you are form india. i am from india also. i am repeatedly asking this problem here. there is no solution. i did chat with support center as well as i went to service center. no one gona listen your problem bro.
i am stuck with 7.1.2 with Oct security patch. my device is not certified after a software update from service center. i went there again and again to certify my device. they dont know how to certify a device. now i am totally hopeless.
in my opinion u just wait for Oreo update comes to india after that go to care. there my be chance that your problem ll resolve. as well as mine. just leave everything and pray to god.
(for check weather your device is certified of not just go to google playstore>left top cornor there is a three bar > then click that > settings > device certification )
i hope u leave a comment your device is certified or not.
I PERSONALLY REQUEST EVERYONE TO COMMENT ON THIS TOPIC