Crank shaft pulley bolt removal?

[TonyUK]

I hope someone can advise me of any tips to get the crankshaft pulley off my 2002 Yaris 1.0Vvti. The engine is still (mostly) in the car.
I have tried the workshop manual method with no success.
I have broken a 3/8ths socket breaker bar on it using the 'starter motor' method.
I then got a 1/2" socket breaker bar, heated up the bolt and give it a good squirt of release fluid before and after heating, then let it cool.
Well, first tries and the battery just wont budge it.
I'm currently charging it up to max, but thought I'd check with you guys
as someones bound to have had the same problem.