Skoda Octavia vRS Mk II Heater issues

Hi, I wonder if anyone on here has encountered this issue;

My VRS heater is overly warm. After about 30 mins is starts to get uncomfortably hot and turning down the controls does nothing. It has to be turned off completely to stop it, but now that the colder weather is coming I would like to get the problem sorted. Easy fix or am I looking at £s?

Thanks in advance.