incorrect data usage reported

I have Fixed Wireless Internet service.  It was installed on October 26.  When I checked my data usage online on November 5, my account reported that I had used 90GB of data in about 10 days.  On November 4, data usage recorded 33GB for watching a two hour movie.  That was the only time anything was streamed.  According to AT&T's own data calculator, streaming a two hour movie in HD should only use around 7GB of data.  The same thing happened yesterday, November 10, when I streamed a football game (1 game!) and used 24GB of data.  I have 16 days left in my billing cycle and I've "used" 135GB of data.  

When I call customer support, they tell me that they can't help until I have at least 1 month of service so that they have history of my internet usage habits.  How will this help when the data usage reported is incorrect?  The customer service rep told me to use the internet as I normally do and that I won't be charged for overages -- because at this rate I will be WAY over the 170GB data limit.  

Based on the previous 3 months with a different internet provider, my usage should be around 160GB for an entire month.  My internet habits have not changed.  I checked to be sure that no unauthorized users are siphoning my internet.  I use a Roku box to stream TV programming, and I am diligent to set it back to the home screen so that programs don't autoplay without anyone watching.  I don't play video games online.  I sometimes stream music, but again, according to AT&T's data calculator, I should be able to listen to 8,500 hours of streaming music per month for around 34GB.  

Someone please help!  

If someone from AT&T sees this, I have a case number from when I called on November 5.