Vi really can't work well with budget phones since most of them don't support band 41. Also like many have mentioned, each area has a good and a bad operator. In my parents' place, nothing except Jio and BSNL work. Jio gives around 6-8 Mbps there.
In my house, barely 12kms from there, Jio sucks. Vi works upto 50Mbps, since my device doesn't support their band 41 and Airtel gives me 60-100Mbps with CA.