Need details for deepening the existing borewell

Hello,

In our apartment in Hyderabad, we have a borewell which is drilled upto 200-300 ft and we have been facing water problem since summer. Inspite of some rains now, we still continue to face this problem. 

I have gathered that by going deeper by another 300-400 ft we can get more water in our area (Barkatpura).

I would like to know how much will be the cost to deepen this existing borewell by another 300-400 ft. Can you pleae suggest people who can help us with this work