Here's an update on some points in my original post:
The issue on voice and Jio VOD happened on Moto G3. When I added the sim back to Lyf Flame 1, while VOD was not exactly smooth the playback was there. Voice worked fine too. I also got 2 OTAs on the phone.
This made me wonder what was happening as never got VoLTE on G3 even though I was on 6.0.1. On googling I found VoLTE needs to be turned on in Lollipop explicitly and some cases in MM too. But then the custom Rom I was on the CyanogenMod 13.0 (Marshmallow) dint have this particular function. I confirmed this with vaibhav too who could see the option for "enhanced 4G LTE mode" for voice and other communication but I dint. So yesterday went back to stock version of G3 6.0.1 and the VoLTE is back. Lesson learned - Check custom Rom if it has support for VoLTE before installing.
This dint exactly resolve the weak signal at my house though. I had a couple of dropped calls but the VoLTE was working. And Jio VOD which was not working at all even at 40MBps, spurred back to life. I was able to watch couple of minutes of Mr. Holmes.
But the marked improvement was there when I traveled to office. The place I had another shitty signal things got better. I am getting 25-30Mbps on the Reliance NetVelocity App and against Reliance Jio Mumbai server in Okala speedtest. But, a big one, here is when I test it against ACT it barely gets to 10Mbps.
Some people in my team tried the VoLTE and they were pretty impressed with the quality to suppress background noise. The voice was crystal clear. I am not using the sim for daily use so cannot comment on whether the quality will remain good in whole lot conditions.
Additionally I have been submitting feedback to Jio on my call and data quality using their app. They even followed up with me on the ticket. The engineering team got in touch and I was told the nearest tower was 600mtrs and that meant I wouldn't get a good connection. So they shared a screenshot claiming that the next building had a proposed tower and couple of planned ones nearby.