It's not just one scandal, it's a whole stack.
First there's the scandal of the original prosecutions including inducing the innocent to plead guilty.
Secondly the fact that as soon as it was discovered urgent action wasn't taken to proactively and promptly quash every single verdict as unsafe. There may well have been some real fraud cases in there but given the circumstances it would likely have been impossible to work out which they were.
Thirdly the fact that immediate urgent action wasn't taken to proactively and promptly compensate those convicted or forced to make up "deficits".
Fourthly that criminal cases weren't investigated and, where appropriate, prosecuted by the barrier presented by the ongoing enquiry and finally that the PO has been allowed to drag out the enquiry for so long with delaying tactics.
It's not just an IT scandal either, it bears on the entire British justice system. There's an old saying "justice delayed is justice denied.". An awful lot of people are being denied justice.