How do I adjust Thermostatic Mixing Valve -Heatguard tmv2 2

Hi,

I have a problem with hot water coming out my tap not being at the correct temperature and someone has suggested that I may need to adjust the Thermostatic Mixing Valve.

Can anyone tell me if:

a) This is something I can do myself (bearing in mind that I'm a complete novice with no plumbing experience)? As long as it doesn't involve taking the thing completely apart etc I'll give it a bash myself.
b) Should I really get a plumber in?

We have a Heatguard tmv2 2 - http://www.advancedwater.co.uk/STOMEMO/A520-373-0612/RWC Heatguard TMV2 Specification Sheet.pdf

The valve appears to have a tamper proof seal but I do have an allen key to release the small bolt on the front. I will try this so long as someone can confirm I'm not going to trash anything!

Thanks,
Dave

This explains it better....
http://www.relianceworldwide.com/site/pdf/uk/heatguardtmv2install.pdf

Inline filters (If fitted) could also be partially blocked and need checking.

Wrong thread