Well in my case, I distinctly remember saying no to PPI because I was self employed (one man ltd co). I have a policy of no buying insurance in any case.
When I discovered it I immediately expressed my shock.
The fact that i was seriously ill and out for six months but made no attempt to claim, should be a strong indicator that I am telling the truth.
I made it clear that I had been mis sold, but that I would now try to back claim. It didn't work.
Now I ma saying, I tried to avoid demanding a refund, but It didn't work, please can I have the money back.
I have no idea if it will work.
My point is that If I was unaware of PPI then the contrct I signed was inaccurate. It could be deemed that the APR defined was wrong because of the insurance element.
As I said, I don't know anyhting about this, just specualting