I first tried a pulley holder tool with pins in, the pins snapped off.
Then I tried the breaker bar/ Bump the starter trick...Just lifted the car up.
Then I tried a blow torch on the bolt and a 1/2 impact gun...Still nothing
So I bought some flat bar and made this;

Might not be pretty but it did the job. Used a 1/2 breaker bar and 3 foot extension. I'm not sure what their torqued at from the factory, but after 30 years and some rust it felt like 500nm.
I've seen the VW tool for this for £50, so for £5 this is a much better option incase anyone is stuck!