Data spike after cancelling cable.

Like many others on this forum, I am also experiencing data spikes Monthly since cancelling cable. My usage for 24 years has always remained between 600- 680. The month I cancelled cable, it suddenly went to 998, the following month 1011 and this month will be higher. No changes to my usage or equipment. Called customer service after the first month and they told me that they needed to investigate a spike on their end not mine, but when I called back for the results, they denied any spike problems in my area or any surrounding areas. Yet the spike continues and gets worse every month.