Unlucky.... but no need to get a chip on your shoulder about a process which is used (in varying but similar formats), by ATC agencies and Military flying and ATC selection boards around the world.
A process that has been evolved and continues to be.
It is not perfect, but no stage of training with NATS or any other agency is. I know of people that in my opinion should have passed the college, have not, I also know of people that in my opinion that have validated and hold a licence, that should not.
To be fair though, you say it is your second attempt. I seriously doubt anyone that has had 2 failed attempts is capable, and they are certainly not worth the cost of the training risk. It's a harsh world, but ultimately, an ATCO is responsible for the lives of thousands of people daily.
If you are so sure you can do it; get a £6k loan and pay yourself through an aerodrome course.