Thanks for all your reply. It really helped a lot and will watch for
the coolant and take coolant with me till this issue is fixed.

I looked at the coolant level and it has decreased around 2 inches
since the past 15 days. When I noticed the level 15 days back the
engine was very very hot (see below). After I saw Elle's post, I looked
at the coolant level (the engine was not driven since 11 hours) and
noticed the decrease in coolant. Will the coolant level will increase
when the engine is very very hot? If yes, the decrease of 2 inches
noticed might not be a correct observation.

To give a little history:
16 days back, while driving with the heater on at level "1", I felt
unusually warm after driving for 8 or 9 miles and noticed the dashboard
temperature going high. I immediately stopped the car and had it towed.
The mechanic showed me coolant on the entire width of the top and over
the radiator and mentioned that the top of the radiator had cracked. He
also showed me that there is no white smoke from the exhaust and also
opened the oil cap (he mentioned he was looking for milky white
formation inside the oil cap to see signs of water inside the engine)
and mentioned the engine has not been affected. The whole radiator was
replaced and the coolant filled up. When driving back (again 10 miles),
the dashboard temperature went very high. I called up the mechanic. He
asked me to look at the level of the coolant and it was full (as
mentioned above). He asked me to drive back to the garage with the
heater fully on. At the garage, he found and showed me that the fan for
the radiator was not spinning and the dashboard was still showing high
temperature. He shorted the temperature sensor and the fan spun. So he
replaced the temperature sensor. I have been driving with no problem
till two days back.

Last week as part of my car maintenance I had the Air Filter replaced,
Transmission fluid flushed and filled up, Fuel System cleaned, put in
new oil and replace the oil filter.

And now this....

Matthew