Hi I bought my octavia 1.6 diesel used just under three years ago, it was three years old at the time, within a few days it was overheating and the dealer replaced the water pump and timing belt, now I'm getting the overheating again, could the car really need a third water pump in six years or could there be another reason, when I put heater on full,the temperature drops back to normal. 

Could be the thermostat that's starting to fail.

Going into the garage on Tuesday, so hopefully get to the bottom of it. 😑

Garry72, I know it was nearly a year ago but did you get this overheating issue sorted.... I had my revised water pump fitted about 20k ago but now starting to overheat under load or driving uphill, could you lease let me know if you actually did get to the "bottom of it" .Thanks