Vailliant Boiler insanely hot water

[HotWaterHell]

Hi

I have a 5 year old Vailliant boiler and for the past few weeks the hot water has been coming out scalding hot. I have tried turning the dial down on the front of the boiler but it doesn't seem to do anything. It is so hot that even with rubber gloves on my wife says it still burns her through them.

I can't seem to find any errors anywhere.. Could a part need replacing already? It is only 5 years old.

Thanks in advance for your help

 

[Last Plumber]

Which Vaillant boiler is it?