VAG G12+ coolant (the orange/red liquid) is not just an "antifreeze". It's also an anti-corrosive package and a "water wetter" (this increases the boiling point of the coolant), so if you've got less than 1 part G12+ to 3 of water, add G12+ to reach that level (presumes car's normally in Delhi; I would advise a 1/1 mix of G12+ and water if you drive in the mountains).
Also, you may have a problem with the pressure seal on the coolant reservoir, so when the engine is cold (first thing in the morning, or when you come off shift if you're a shift worker) remove the filler cap, and clean both the top of the bottle and the seal on the cap. After this, it starts looking like you may have a coolant leak, and diagnosis gets difficult when you can't see the car.
Thanks for your valuable input, I checked that found coolant level is very low that point to coolant leak, then i go to workshop. Mechanic checked and found there is leak from one of horizontal pipe (white). They replaced it.
Neill, I have one query regarding timing chain. Is there any limits after which we have to change it. Actually a mechanic told me to replace it because it completed 64000km.