GTV6 1986 Petrol cap problem removing

[sval]

Hi
I have a petrol cap where the key turns clockwise and anti-clockwise. However I'm unable to take the cap off as it seems that the tabs that hold the cap in place are not retracting. I have sprayed WD40 into the lock chamber, still no good.
Has anyone had a similar problem and how did you fix it?

Cheers
Steve