Creation Finance are causing me issues

Did they really say all of that or is that your interpretation of what they said?

that there were no rules about mis selling then.

There are no rules about misselling now. What I would expect them to say is that you bought the policy 15 years prior to regulation of insurance and rules applicable to sales made after regulation do not apply to those before.

They have then said that when the FCA started looking into mis selling in 2005

The FCA did not start looking into misselling in 2005. That is the year that the FCA regulated insurance for the first time.

they sent me a letter making me aware of the PPI attached to my product (I never received this).

What date did they say they sent this?

They are using this as the reason why they will not compensate as the letter was sent over 6 years ago and I did not act upon it.

There is no 6 year rule that a letter can start. There is the 3 and 6 year rule. 6 years from the original purchase and more than 3 years from the date the letter was received, whichever is longer.

I have been told that the finance ombudsman will not act either as it was prior to their set up!

The FOS cannot look at pre 2005 sales unless the firm volunteers or the firm was a member of an earlier body (such as the GISC or ABI)