No Heat

I would have given the first one no money. But, never mind that. It sounds to me like the thermostat is not opening.
Now I am using past knowledge from VW Rabbits but VW has remained consistant in many part in many vehicles so it is unlikely that there is alot of difference.
So, if you got a bit of time and some tools and some idea what is going on. First way is gonna be the most simplest and should fix it. Drain the rad. Keeping the fluid. Now refill the rad FIRST by pulling off the top rad hose that goes to the engine and pour the fluid in there until no more goes in. There will be air coming out but that is what we want - all the air out. Now the one side of the thermostat is under fluid.
Now add fluid down the rad filler neck until it is full, and put the excess in the overflow container.
Once all that is done. Start the car and let it warm up and open the heater valve. Which by the way you can see in the engine compartment on the heater hose is a plastic shutter with a wire cable attached to it. Move the controls one way and the shutter shuts off the flow to the heater core, move it the other and the shutter allows the hot fluid from the engine in. If that works visibly there is no reason to think that there is a problem there. If never sure if open or closed, go half way.
You should now get heat.

If not. Perhaps the thermostat is the problem and is not opening. (But then the engine should be overheating.)
At this point you would have to let the car cool again and remove the thermostat and put nothing back. Everything will still work without a thermostat. The difference is the car takes longer to warm up as the engine must heat all the fluid(in the engine and in the rad) instead of blocks of it. But with the thermostat gone, that is not the problem. There is nothing else. Blocked rad my butt. Then the rad would be blocked as well.