Need remedy for the borewell struck with rocks

Hello,We have dug a 4.5" bore last week in our house at Melmanvoor, Vellore. Our house is on the outer border of Sauperi lake (which remains dry). At about 40 feet, we struck water and drillers said that there was lots of clay in the water at this level. The driller decided to not to drill any further than 75 feet, as they had struck 'koolankal' type rocks (pebbles) and told us that it was not possible to drill anymore. We were told that with a one inch pipe we should have enough water for our family of three people. They have put PVC pipes with holes to ensure that the bore doesn't collapse due to clay and we keep getting water supply from the bore. So now we have 75 feet column of bore with the water level at 20 ft. Previously in 2005, we dug a 200 feet bore which did not yield any water and we abandoned this well. My questions are: 1) Is there any other methods or organisations in Vellore who will be able to drill deeper to yield more water? 2) Please advise, if our water supply will be enough for a family of 3 persons. 3) What type of motor pump is advisable to fit to draw water for the borewell? 4) Will it be advisable to dig any deeper in the site that we abandoned at 200 feet? 5) Please provide address of person/organisation in Vellore which deals with borewell and water table detection using government approved scientific methods. Many Thanks.