New borewell filled with boulders in Bangalore, Karnataka - Need an economic solution to remove the boulders

I had drilled borewell at NRI layout, Ramamurthy Nagar, Bangalore on 19th March 2010. The report given by the borewell company is as follows,
660ft - First water source {1"}
705ft - Second water source {1/2"}
and total depth of 820ft.
Spent around 1.3lakhs

The bore well person told that there were boulders at 660ft on that day.

Recently I had approached for motor erection to my shock they told the current depth is only 554 ft and the water is only 4ft and the motor cannot be errected. (date 27th March 2010)

I am collapsed with the out come I am unable to concentrate on anything.

I had asked the borewell company for solution and they told the boulders have filled in so, you need to flush the borewell and go for 4 1/2" slit pipes for 820ft.  The cost quoted by them is more that cost of new borewell.  I don't have way out.  I require a good solution. please suggest.

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