Richie-rich,
Don't let it get you down, mate.
For me - I did as many practice exams as I could get my hands on. Every question I failed in the practice exam I would go back and restudy.
If you've got the ATC textbook, then get the Bob Tait, or vice versa. Sometimes when you don't fully understand the subject, it helps to get it explained a different way.
If you can, get a study partner and test each other.
GL
