2000 Passat Coolant Problem

Hi all, recently while driving within the city, I got Check coolant indicator flashing. I didn't check the engine temperature at that time (should have!!). I had to stop the car all of a sudden and get it towed to my house. Now when I checked the coolant level, it is about 4 inches below the min. mark and there is very less coolant in it. My dealer is suggesting that I add water and drive within the city and see. I cannot drive down to the dealer as it is about 50 miles away. Does anyone have any suggestions as to whether I should coolant instead and get it checked for coolant leaks? The worse thing is I got the cooling system checked 2 days before and they said they drained the coolant and topped the tank with coolant. Any suggestions are welcome?

Miles on my car: 36,000 plus

Thanks,
KK