G'day jackjoseph92,
Only you know if you're guilty or not!
WA Police has a page with
Criminal Offence Descriptions - Theft/Stealing:
The unlawful taking or obtaining of money, goods or services, without the use of force, threat of force or violence, coercion or deception, with the intent to permanently deprive the owner or possessor of the use of the money or goods. This category of offence includes the theft of vehicle parts or the contents of a vehicle.
Its interesting if the Police have charged you because in your case you have suggested that you didn't have the
intent to permanently deprive the owner of the goods. Intent is needed to prove the theft/stealing charge. You also said you went back and paid for the fuel. (
Here is a recent article about petrol drive offs in Western Australia.) It doesn't seem that they could prove the intent element ... unless you've done it before?
Legal Aid WA has an Infoline you can call for some legal advice (1300 650 579) and you could also make use of the Legal Aid duty lawyer on the day you have to go to court.
Hope that helps.