(However I have heard of a successful legal challenge to such refusals, anyway).
I suspect that the legal challenge you are referring to is the one that TH referred to about an IR. IR is covered by JAR FCL, although each member state can decide if they want to accept the exams of another member state. The UK wont. If you do the exams in another state you have to do the training in it as well. However at there discretion they will add the rating to a UK licence in accordance with JAR FCL.
I know PPL exams are different from state to state, but I read of cases where some CAAs recognized exams given in other JAA member states, but probably that was about CPL or ATPL rather than PPL.
Do you have specific referrals to that rule? That's a UK only policy or part of JAR regulations?
I hold the UK PPL question bank and those from another JAA state as an Examiner. The PPL exams are not covered by JAR FCL. As I mentioned in a previous post they are NATIONAL exams. There is no JAR syllabus for the PPL nor is there is a common question bank. The only record of the exams are those kept by the school and the entry they make on the application form that goes to the NAA for licence issue. The number of times you can sit the exams comes from the number of exams sets we hold, there is only a fixed number and of you exceed those then you have to have a set written for you and take them at a NAA test centre or wait for the time limit to expire and start again.
As IO points out a number of states have bought in the UK exams to save producing there own. I know Cyprus also use them and if memory serves right so does Malta and I bet there are others if you dug under the hood.
In general the content is pretty generic and no one states is much different or easier than an other.
I really don't know what you are having a problem with, the exams are not difficult, use a confuser or computer software like the Dauntless Software question and get stuck in. If you are still struggling there are plenty of people who can do custom Ground School for you. Derek Davis in the UK is renowned for crammer ground schools. I am sure there are more people like that in your own country. Or you could even get your flight school to do the job you are paying for and actually teach you something.