Not sure where you got that idea from. This has been discussed on here previously.
My understanding is that the PL rules don't have a specific limitation clause but there's a six year limitation period in English Contract Law, so generally contracts over six years old (longer in some cases) are time-barred from legal action.
However if there's suspected criminality involved then that limitation can be laid aside. And we are being accused of providing false accounts, which is a criminal offence. So they can potentially go back as far as they want.
But, as I've said before, and so has Stefan, the Mancini contract is a complete red herring. Even if we were found to have breached the rules over that, it's not material in any way, given we were making huge losses at that time.