DMC,
Wow sounds like you just had a bad run mate!
I know it can be disheartening when someone who is obviously not having a good day tells you not to bother. That would have hurt, but mate, you really should just give it one more crack!
I'm another case of pilot/extensive aviation background/mid 30's second time through the assessment centre and I made the cut. All I'm trying to say is, by all means, have a backup plan, but if it was your dream job and something you really truly wanted, screw the HR department and give it your best! you get a second chance for a reason and hey you never know, you just might make it.... isn't that worth the risk???