once cars running hot. check the rad pipes to see if ones still cold.
Do people even read before posting????????
both mechanically inept and dumb it seems!
The pipe that connects to the top of the radiator (passengers side) was red hot to the top of the radiator but anywhere past 2 inches into the radiator it was stone cold (Im guessing this could be radiated heat from the thermostat)
When I turn the car off recently the fans both spin up full chat for about a minute and then stop (this duration can be reduced by squeezing the top radiator hose) I guess its moving the water near the temperature sender?)
The bottom hose and entire radiator is stone cold
The return pipe that goes back into the filler tank is red hot and when I squeeze the top rad hose the tank bubbles so the return is working
Waterpump is working due to water flowing back to expansion tank.
We are assuming since he said it was driving that the engine fans are not involved as the airflowing over the rad means they are not needed.
While a bit pikey having the heaters on acts as a mini-radiator as it uses the heat in the engines coolant to warm the car interior by passing air via heat exchanger so using this would effect cooling which combined with the faults RE coolant hose temperatures points to a thermostat.
OP replace your thermostats with genuine units. Manual GTIs have 2 (main thermostat and a smaller inline one) dsg ones have 3.