The coolant temperature on my VRS is playing up, it will sit at the 50 for ages and occasionaly move up to 90, but its intermittant and drops back and forth while getting there.

I have plluged the car into VAGCOM and it has no issues logged in relation to engine temperatures, would this mean that the sender is broken? Or would it be the stat?

You can see the temps on VAGCOM. If it goes slowly down when on the move itll be the thermostat. Fairly fiddly job, youll need some long quarter inch bars with 5mm allen bolt and probably a universal joint.

PS Get a genuine dealer supplied one too. Replaced mine 6 months down the line from GSF, not too pleased.

I'd use the VCDS because it could be the thermostat, or the temp sensor feed to the guage.

Also, has the fuel economy taken a turn for the worse combined with the guage starting to play up? If not, then it's probably only the sensor feed to the guage.

Thermostats faulty, if it already hasnt logged codes it will soon