Having a similar issue being that one day I went from having no glu credits to having negative 60 credits later that day. How is that even possible? If you got any help by now with your issue could you please lend a helping hand or anyone for that matter?
No doubt the game is fun and I will continue to enjoy playing it, but dealing with the bugs can be quite tedious or better yet time consuming; whereas we already spend quite a bit of of our day playing this game. :-)