Time to be done with it. She doesn't really want to pay what the cake is worth, can't get her act together (believe me, if it was really THAT important to her she would find someone technology proficient to help her get the picture to you) and you don't want to do the order anyway.
I would call her and tell her that you are now completely booked with other orders and won't be able to make the cake.
This. Just call and tell her you are sorry, but you are now booked. Wish her the best with her event.