Overage Charges - Please Explain?

I watched my internet usage like a HAWK this month and i let it go JUST over the allotted 1024 through the 25th of the month which is supposed to be end of the billing cycle just to see how the overages work... on the 27th i resumed normal activities. Well, i just received my Cox bill and you guys are claiming i went over by 150GB by end of day 05-25-17!!! I know for a fact that this is absolutely false... if you are going to claim billing cycle is through the 25th but push it out further to try and steal extra money from me you guys have officially lost us as a long time customer. This is insane!