Clinty83,
The fact that you had those hours (and your mate with 2000hrs) etc was probably one of the reasons why your application was successful and you got to Stage 1.
But then the slate is wiped clean (like with all subsequent stages) and you start on an even keel.
So thats the English Test, Reasoning Test, Aviation Knowledge (that a guy with 0 hours can actually learn in a week) and an Interview (which is with HR and not pilots).
Now for the 4 points I listed above, 3 hours or 3000 hours is irrelevant. I'm pretty sure the the CPL/ME IR does not include reasoning test training.
I'm guessing therefore that you were probably ill-prepared thinking that your "300 hours" was enough to get you through when it actually only got you tthrough to Stage 1.
And if you had made it to Stage 2, you would have had to do 2 group activites. Again 300 hours means nothing if it is obvious you couldn't work with your team.