ASDA account opened on line with PPI

Hi,

I am totally confused.
I opened my credit card account with ASDA back in 2008.
Have no paperwork at all.
I have been struggling with repayments up till today, as my financial situation is poor.
I haven't realised what PPI is until I saw all adds in TV. Then I discovered on my statements it was named as 'Balance cancellation cover', rather than PPI.
I did cancel it and send a letter of complaint about miss sold PPI to the provider.
After over a month I got a letter from Santander, who took over GE Money, after reviewing ASDA agreement and account details, PPI was added after accepting my on line application form.
Obviously, I did return everything signed. At this time, I cant really remember what paperwork I have received - as in apart from contract, anything explaining what PPI / Balance Cancellation Cover is.
I didn't need PPI and am unable to prove if I got anything explaining what it was. Also, looking at the conditions I should be able to cancel it within 6 months from the time I got my card - do not recollect any paperwork.
The other thing is I never claimed anything I would be entitled due to PPI conditions. The interest from card itself and PPI were causing a massive impact on my financial situation, which was reflecting on my bank account charges.
Is there a point for me to write to FOC?

Thanks for all your advices,