Green mountain energy scamming?

Good afternoon, last month I received a bill for my 1450 SQFT townhouse, the months prior have been about average $60-$75. I'm on the free nights (free from 8PM to 6AM), and sure its been getting warmer out, so last month jumped up to $190. Whew.. I better start doing something different. So for the month of July I started turning the A/C up from 76 to 80 degrees when I'm gone for work during the day (6:25am – 5:30pm). Now this months bill is about to come up… and I'm looking at $253.47….? What? Isn't that the opposite direction it should be going? Of course all they offered was "average billing" which means you'll pay for less during the summer but it'll be more during the winter, your essentially paying the same at the end of the year regardless. Just wondering if anyone else has a similar story or has some insight that I'm missing. Thank you in advanced!