In app purchases, now the game has been changed

I made several in app purchases over the last 6 weeks to level up a few characters on a Marvel game. Now, the developers have changed the specs of the characters to "fun balance" the game. This has essentially ruined my characters, not to mention the time, effort and money that I put into the game. How can the developers be allowed to change a fundamental piece of the game like that when it is a purchasable variable? Do I have any recourse here?