The first thing I thought here was that you probably stayed with the wrong instructor. The first thing I have always tried to teach my students is that their training is about THEM not ME. If they can't learn from me, they need to find a different instructor. No hard feelings.
That being said, you can get hired 91 corporate, 135 or 121, but you can't bust again. That will probably mean that you will need to take additional time to train for the remainder of your ratings to ensure you know the material inside, outside, up, down, backward and forward. Make sure you do a thorough self evaluation to determine the cause of your past failures, what you learned from them, and what you can tangibly do to overcome them going forward.
Good Luck.