Disclaimer: I am not a lawyer, I am a plaintiff in a defamation case. You should not rely on this information as legal advice. You should seek legal advice.
Contact the servo and apologise and ask for your picture to be taken down.
Sadly because the cameras were placed in a public area and were visible, there is a reasonable expectation (according to the Surveillance Devices Act) that you may be filmed or photographed.
It is arguable that the publication of your photo is defamation, it is a long-shot in terms of defamation, but you may technically have a case, except all it says is "Not welcome", without any context.
In defamation law, you would have to list the 'imputations', that is "the message, insult or innuendo conveyed by the publication". Examples might have been things like "this person stole petrol" "this person shoplifted" etc -- but all it says is "Not welcome", so it's difficult to say what a reasonable person may impute.
Furthermore, you would have to demonstrate that you are identifiable in the publication. Is your face clear? Would the average person be able to identify you? How many people are likely to be able to identify you and then think less of you?
In practical terms, if you were to pursue defamation, it would cost you approximately $1650 to have a lawyer write a "Concerns Notice" - this is a complicated document that outlines what happened, what the imputations are, who the audience was, how you were identifiable, how your reputation was harmed, and what you want done about it, e.g., taking the photo down, them publishing a retraction, providing you with a copy of the retraction, and apologising to you.
The other side then has 28 days in which to provide an "Offer to Make Amends". They will almost certainly simply take the picture down.
If the judge finds that their "Offer to Make Amends" was reasonable, e.g. that they would take the photo down, then you would certainly lose the case later.
If you believe their response is unreasonable, you could then commence defamation proceedings, for about $4,000 – that is just the starting cost for a Statement of Claim. The court filing fee is about $1,000. From there it will most likely get directed to mediation, where again, the parties will be encouraged to settle. If it goes to trial, you are looking at $20,000–$100,000.
The judge cannot force them to apologise, but they can force them to take the photo down, issue a retraction, and pay your costs and potentially damages.
So in practical terms, the best advice would be:
1) If the photo doesn't identify you clearly, don't worry about it
2) Write to them apologising and ask them to take the photo down.
3) If that fails, try escalating the matter up their corporate hierarchy, and threaten defamation.
4) You might try calling on the police to come to the servo and assist -- I'm not sure they'll help, but maybe?
5) If that fails, spend $1,000–$2,000 on a "Concerns Notice"
6) I really doubt you should go further than that because it won't be worth it.
For the record, I think you should have worn the mask
