Bollocks.
British "court orders" can't bind the UK government for years. They can always change the law, if they want to. It's pretty much a one-line law: "As an exception to the sanctions against Iran, the UK government can pay Iran the refund it owes for the cancelled tanks order".
And in those court cases, it was the UK trying to get out of paying. And then trying to get out of paying interest.
Regarding her being a dual national ... so what? She wasn't kidnapped because she had an Iranian citizenship. She was kidnapped because she had a British citizenship and lived in Britain and had a spouse in Britain and photogenic children in Britain. And she was female and photogenic. All of which made her an ideal pawn for negotiations. Her spouse could talk to the UK press to apply pressure to the UK government. The photogenic female victim, and caring spouse, makes it a good sob story for the UK press. The photogenic young children makes it an even better sob story for the UK press.
And a British government minister then made up a false story about her just being in Iran to ... do something that would have broken Iranian law. And announced it on TV as a fact. Like, how big of an idiot do you have to be to run your mouth on something like that, and give Iran a perfect excuse to keep her in jail.