Pending purchase problem

Hello! I was really enjoying the LoseIt! app, so i decided to buy the monthly premium ($10) but for some reason they charged me the anual premium ($50!!!). But i can't afford it. I simply dont have that money in my bank. So now there is a "pending purchase" on my apple device even though i cancelled the anual subscription and i cant install apps and/or update them. Also note that although it says cancelled it appears in the active section.