Heat (though not fan) always on?

Take it back and tell them about the problem. The blend air door sounds like it isn't working. They could have bumped something or done something that is causing the problem.

The blend air door is what determines if you get heat or cold air from the system. It is located near the heater core and chances directions when you want heat so the air blows across the heater core and then the other direction closes the heater core box and passes it directly into the vehicle or past AC components.

I hope this helps.