I have had problems with my heating in car.
A couple of weeks ago my car overheated. Checked and the coolant was very very low. Took it to a garage and they replaced the thermostat housing due to a crack.

I am now noticing that when i move, the car gets warm air through the blowers, however when stationary only blows cold air. I'm not sure how much coolant was in the car after the garage fixed it but if they filled it to max, it appears to have lost a bit over a week. However wondering what could be the problems and if the garage should have spotted it.