Recently I received a text from coz that I was up to 75% of my data usage. Then right after, a text saying I was at 90% and 10 minutes later saying I had used 100%. Since then, I have over used data ...
Yes...subscribers have complained about unexplained chunks from their data caps. Cox, however, will blame you by insisting an unauthorized user exploited your weak password.
First, you could log into your Cox account to review the charts depicting your data usage. If the charts confirm, you could log into your router for any unusual connections. You'll need to know the MAC addresses of ALL your devices to discern an unusual connection. For example, you may conclude 2C:54:91:88:C9:E3 isn't an address of your devices. If you conclude this, yeah, someone hacked onto your wireless network.
However, an unauthorized user may have cloned 1 of your addresses, so you'll have to identify the device and the download time(s) to verify if this really happened.
It's good practice to annotate somewhere the MAC addresses of all your devices so you can investigate this stuff.
Cox could drilldown on their logs to analyze your ports, sites and timestamps but if Cox will do this for you becomes the question. If you want to challenge, you'll need to do your homework. I mean...128 GB in 10 minutes is some serious data funneling.