While the voice connectivity is good in most places in Kolkata, there customer service is shoddy to say the least! The 4G is not stable throughout.
I have had a problem with the connectivity in my office. Their engineer visited the premises and said that a booster needed to be installed. This was over a YEAR back!! Despite repeated e-mails and phone calls, no booster has been installed.
In fact, they have kept on postponing the date of installation by 1 week every time, saying that we apologize and it will be done next week. One of their personnel even told me on phone that a booster is very expensive so they are taking time! Time more than one year!! And that they don't know when a booster might be available.
I have faced a similar problem with the billing for international roaming as some other people where Vodafone does not use pro-rata method of billing.