I think I might've screwed my Pwc business insight application ...

You can't really submit any grades for AS or A2 seeing as you haven't done them yet. I would explain (if possible) that you have done mocks in AS and these are your grades. Don't try to make your own predicted grades. When is the deadline?

I've already submitted it. Also there was no way to explain it since all you can do is fill it in.

What scheme year are you applying too ?

Also I think it's best if you call them and correct the mistake asap because it could affect your application