WGT won't do anything for you on this. They're third party offers over which they have no control. To offer advice, I'd need to know where the offer came from. That's a somewhat unusual credit amount for Peanut Labs, so I'm thinking you were on a mobile device.
Regardless, your best defense is to get a screenshot of the page as it nears the end. Most react quite positively to polite, well worded complaints. I have had very good responses from Peanut Labs.
Good Luck.