I had the same thing happen. I leveled to 58, bought the car, began the quests and got reset to 57. I contacted EA who said there was no record of a back up save or synch. They did give me money back. I didn't lose all of my XP. EA claims they are working on this as well and did say others are having similar issues. They recommended synching and logging out every time. FYI: I was synching and logging out after big milestones like leveling up or something similar. It didn't help as EA had no record of me playing at all yesterday. Just take screen shots to keep track of cash and donuts before doing anything major like buying a main quest item, spending donuts or when you receive donuts.
I don't think it will get fixed, but maybe EA will prove me wrong.