Nice try! Yes, previous governments could have paid however when the international court ruled in Iran's favour in 2009, sanctions meant it couldn't be paid without breaking the law.
A delegation from Iran to discuss the debt were locked up as soon as they arrived in the UK, that didn't help...
This. They bought some stuff of us, we didn't deliver the goods. Refund them and retain some of the moral high ground. Hopefully that would improve relations between two countries and also get her released.