Massive data spike

I have been an internet customer for over 20 years and am absolutely fed up with the unsubstantiated data spikes that have hit my account over the past year.  Without changing anything related to internet usage in my home the data that I have used has managed to go from 58GB to over 2000GB? Please help me understand how this is at all possible?  I have done everything that Xfinity has suggested and been a loyal customer for decades.  I am quickly realizing that customer service and honesty are not qualities that are not priorities for Xfinity