How frustrating. I passed my actual SAT exam but was told that I had failed the 2 mocks that I took in the lead-in to it (some months ago now).
I could not understand where I thought the mistakes had been made and so I queried a few things with my training provider. After a few conversations between them, the ICB and me, it was agreed that some of the questions had been marked incorrectly (both mocks should probably have been passes). Whilst this was admitted, and they have now changed the format that one topic is now tested in (for clarity), my record has still not been updated as I was told it would be. Nevermind.
Anyway, based on my experience, I would definitely recommend asking for further explanation of the areas that were flagged up to you, as it could be the difference betweeen a fail and a pass! Whether you should have to pay for the privelege is highly debatable, in my opinion, but I know that is ICB's general policy.