Got it serviced specially underside of engine as it was hell dirty due to oil leakage and dirt accumulation. Guy used Caustic soda then kerosin oil and finally surf to wash under side and it was clean as new 
Changed left CV joint seal and oil sump cleaned and assembled back with silicone. Problem solved in 430 rupees only. No more oil leakage
Other mechanic was saying to separate the gearbox and take it to gear wala. total cost suggested by him was 3500-4500.
Moral: its always good to get second opinion.... :P
