PPI Rate used

JPears

Please accept my apologies if this has been answered before, I have read the stickies, googled and looked through the first 6 pages of this forum to no avail.
I am looking for the typical rate per month charged per each £100 on the balance for a Lloyds(TSB) Duo Card. I appear to be coming up with figures from 0.5 to 15%! Or does the rate depend on the typical base rates at the time? Bearing in mind we were at 15% base rate late 80s/early 90s.
Lloyds have admitted a PPI claim where I wasn't aware I had PPI had been taken out and I have been self employed thoughout the majority of the time the card has been held, making any PPI all but usless - 1985 to present (self emplyed 1989 onwards).
The amount offered is very low given the length of time the account has been held and the balances sometimes held on the account.
The "calculations" supplied are very brief and appear to be guesstimates of time, balance and rate, with no mention of any of these as a specific. I have the majority of statements going back at least 15 if not 20 years (the joys of being self employed/HMRC) and wish to start doing some calculations myself before rejecting the offer from LLoyds.
Many thanks in anticipation of some help.

[Deleted User]

If you have all the statements going back twenty years, then you can see exactly how much credit card PPI you paid, as it appears itemised on a separate line each and every month.

Did you never check these statements? Otherwise, it's very difficult for you to say you were "unaware" of the PPI.

If your statements show you paid more PPI than the Bank are offering to refund, you should submit this evidence to them. It's possible the Bank no longer has complete records of your finance and has had to estimate your redress.