There are uncountable institutes and coaching centres across the city, there are many unqualified professionals who have open up coaching centres to earn money.
If you are willing to master English language, enroll yourself under the Best Institute of Kolkata. The strength of the class plays a significant role in how much attention is being paid to the students. So, one teacher every six students is the best ratio but, many do not abide by it because there are so many students seeking tuition
It is recommended to research well about any institute where you are planning to take admission. Only then you can find a good institute for learning English.