Basically, it's my fault for fucking up the application, but at the same time, I wouldn't have received the offer even if I did fill it all in correctly. If, however, I did nothing for 6 months (no university) and then filled out the application, I would have been accepted. Also, if I had have got my first application correct and applied for Access Melbourne (the December 2013 application), then I would've been accepted right from the start and would never have had to have dealt with any of this in the first place.
I guess the real issue here is not that I've been rejected from my dream university, but rather that I cancelled my enrolment at RMIT the day before this email was sent to me. Currently, I'm not a university student at all. I've got myself into a lot of mess and I am worried that I won't be able to get out of this

Edit: At least I've learnt one thing: in the future I am going to re-read my VTAC application 100+ times to make sure that everything is correct and perfect and that I haven't missed anything. It's crazy what the consequences are for forgetting to fill in part of the application.
Edit2: The worst part about this is having to explain all of this to my family and friends
