Ok so I took my car to my dad yesterday and we spent a good few hours trying to locate this other sensor. Going by the image you posted above of your engine to start with we couldn't find it at all. So we used the Volkswagen diagram and looked at the two places it was suggesting and it wasn't there!

My oil filter screws directing into the block so it wasn't there and it wasn't at the side of the engine like under the timing belt area like it was directing in the picture.
I honestly have no idea.
All I did was replace the blue one with a black one I also got from GSF to see if that made a difference and it is now slightly worse so I've got to change that back to the blue one.
On another note, I did change my air filter for what looks like the first time in it's life (the filter was literally black xD) and now my car seems to have more acceleration...although that could just be me thinking it has

regarding the sensor though, no idea what to try anymore