Honestly, man, you're pretty much shit out of luck on this. I had the exact same issue, but thankfully didn't use all of the platinum I got from Unmastered's scam. In the end, I still wound up paying over $200 out of my own pocket to play the game again. You're likely better off finding a reputable seller and buying a new account. That having been said, if you absolutely cannot buy a new account for whatever reason, you're going to need to pay the negative balance. It's possible to do this at an extreme "discount" using Prime Access purchases, which give an inordinate amount of plat for the amount they cost, but you're still looking at over $500 in the end.