My superb gas a heater problem it's either stuck in cold or holt. I need to move the nob all around few times to get something change but sometimes this does not help either.

Any suggestions on how to fix it, would it be a easy fix ?

From similar issues I have known about on a Polo and an Octavia, the best steps could be:

 

1) Get someone / garage to read any fault codes (doesn't have to be a VW group dealer - anyone or any place that can read VAG fault codes should do).

2) Look for faults with the flap motors and/or the temperature sensor readings.

 

On both the cars I mentioned, the motorised flaps that control the temp (2 of them were behind the dash) were failing. Playing with the controls could fix it for a short while but the issue came back. My brother told me this is a common enough fault across VAG vehicles.

 

As for ease of repair - perhaps wait for someone who knows the setup in the Superb to chime in. Replacing them on the Polo was a pain (dash removal) but I think the Octavia was easier (access under glovebox/some centre console work)  in comparison .

Cheers will try that