How to calculate interest on PPI claims

jp1223

I am in the process of claiming back PPI for a loan that was taken out in March 2004 over 4 years via Tesco Finance, my last payment was made in March 2008. I didn't have the paperwork, but have written to the provider with my £1 and now do. PPI was included, but I know that I was pressurised into taking it out, despite the fact that I was in employment and had insurance through my work (in fact at the time I even worked in a Tesco store!) Anyway, I have calculated that the PPI loan was 18% of the total loan, so I have added 18% of the total interest paid to my claim. However, they have had my money for 4 years since I stopped paying them anything, so surely I should be entitled to interest on the whole PPI amount, including the interest I paid them too? how do I calculate this? my loan was 16.9% apr, I did think of adding 20% of the amount for the whole 4 years, but this is still less than the 16.9& apr I paid them over the same period of time. Can anyone assist me? I don't want to risk delaying settlement, or even blowing my chances by expecting too much, but at the same time don't want to be going in too low!

[Deleted User]

If you are successful, all your PPI payments will be refunded to you and you'll get a flat 8% interest payment.
All your other "calculations" are irrelevant.