I also had a complete nightmare with Met - thought I couldn't learn anymore of it but still couldn't reach 75%!!
I did a 1 day course with Steve Francis who was at Oxford at the time, not sure where he is now though but i'm sure he's still in the business! Went from 72% to 95% on my 3rd attempt - he was bl**dy amazing!
I'm sure someone on PPRuNe will know where he's working because he was worth every penny spent that day.
Keep slogging away mate, you'll nail the bug*er....