Key financial information incorrect?

[shouldbworking]

hypothetical land here..

The APR on a HP agreement is listed in the key financials as X, however, determining it via online calculators indicate it is not that, it is in fact Y. Y is listed at the bottom of the key financials as 'Interest at an equivalent rate of Y is charged n the amount of credit from the date of first payment blah blah'

Does this mean the agreement is technically invalid? am I being dense and using the online calculator should not be expected to come out with X?

[mcflurry]

Are both calculations based on exactly the same amounts and criteria?

[crazy about cars]

Sometimes there might be a percentage of admin charge applied to the calculations from the finance provider.

[shouldbworking]

The calculations via both the online calculator and on the agreement have the same admin charges included.

Interest doesn't look to be charged on these values, with them just being lumped on the charge for credit.