I have just had a Forge recirc valve and spacer fitted to my car and after two days of it being on the check engine light has came on, so I wheat to my local garage and had it diagnosed and it came up with Turbo/Supercharger Under Boost I take it that this is caused from the Forge valve as I've never had an issue with the car until now? Any help on this matter would be appreciated. Also the engine has cut out on me twice and this is causing me great concern Thank you.

You would be better asking in the relevant Octavia section, than here.

You either have a boost leak or need a stronger spring fitted to the forge valve.

It has the green spring in it. And I've not had a re-map. Ill have to get the car on a ramp and see if a hose has come off.