Thanks Lord Galathon, I did a little trick today, I took a small perrier bottle, and added 50% coolant roughly 250 ml , and 50% water 250 ml, shook it and dumped it in. The base water level is a bit higher than normal cool level marking now, but seems to be doing better now. I usually ask my garage guy to check fluids, and he's always like yeah yeah ... its ok its ok. 2 months ago, I just added a little water to the coolant bay , no coolant , ( as the garage guy said its no biggie so I didn't want to screw it up ), but I guess I am going to have to be more attentive .... and find a new garage guy.
I'll keep an eye on the spark plugs too, as per your advice.