Negative balance

Hi, I been playing plants vs. zombies 2 since it came out, I have been saving my coins till I had almost 400 million, at the last update, all my coins turned negative, so now I am NEGATIVE 400 million. Why is this happening I can’t buy anything, can’t do anything I go in every day now just to play the videos to get coins. Why is this happening and how can it be fixed. I am not happy right now please help!