plus interest plus an additional statutory 8% per annum accumulating compensation amount
I'm not entirely sure how it's worked out, but I think it's based on the difference between your annual repayments with and what they would've been without the additional PPI.
Then 8% is taken from that amount each year and added onto the final settlement figure.
All I know is that it added nearly an extra £1.5k to my final payout.
As LGF says though, this is a tax declarable sum as it counts as additional income.
What happens if you don't have any paperwork and are not 100% sure of the company i.e. it's one of two?
It may still be worth contacting whoever you think you had your loan or credit cards with to see if they have any records of you.
The hardest thing will be proving that you are who you say you are when making such requests without any firm information to back things up. Security checks when you've forgotten passwords and previous addresses are always fun.
The lenders are however legally obliged to supply any account details. Ask them for a repayment schedule for your account, or just ask them directly whether you had a PPI policy or not.
The banks and lenders should be contacting any of their customers if they had been sold PPI in the past.
For example, and rather ironically, I received a letter and PPI claim pack from Egg banking a few weeks after I'd contacted them to initiate my claim. My contacting them would have supplied them with my current address, hence the letter from them.
I suspect the biggest difficulty for the banks is contacting customers whose contact details are out of date.
But it's always worth a try...