Open Question: Is there a legal requirement for all debts owed to be on your credit record ?

In 2002 I got a 100% mortgage through my estate agent and they loaned me a further £3k to cover moving in costs. The APR is absolutely mental at nearly 30% - I'm thinking of using Kerobo.com to write the loan off based on the creditor (who has changed hands twice since 2002) being unable to supply a copy of the original credit agreement. The only issue is... Kerobo wants £495+10% of the loan value+VAT before they'll look at the claim, they will however refund in full if the credit agreement is watertight. The loan itself doesn't appear on my credit record from CreditExpert.com, it never has.... does this therefore mean that it is unenforceable ? Is there a legal requirement for all debts owed to be on your credit record ?