Comcast wants to "come in and inspect my cables" because of higher than average data usage.

My father told me that a Comcast tech came to his door and said that his data usage was higher than normal for the area and that he would like to come in and check the cables, cable hookups, etc. He also said that the wires going to the house could be dry-rotted and that could be causing the higher data????

I checked my dad's account and his usage was between 150 and 180 GB a month, which seems normal for someone who uses Netflix and streams music, etc. (Mine is almost double that, but I game a lot and don't use Comcast)

The whole thing seems fishy and Dad doesn't want them poking around all over the house. Does anyone have any suggestions or thoughts?