I appealed when I failed my driving test. I got 2 minor faults, and 1 serious fault.
The serious fault should NOT have resulted in a fail - but it did.
I appealed, with my driving instructor backing me up, and bascially the DSA said that they were happy the test had been conducted correctly, so I wouldn't get a refund.
You can't appeal against the decision I don't think, just against the fact that the test was not conducted in accordance with the regulations. And as other people have said, it's your word against theirs...