Download speeds dropping after midnight

I have the 2 gig service and get 75 to 80 speed on my wired connection during the day but every night betwen midnight and 1 AM the speed drops to 4 or 5 and sometimes drops altogether and doesn't come back up till morning.

It still shows as connected but just no Internet.  If I am only getting the speed I am paying for during the day I feel the charge should be reduced by 33%.

Anyone else being subjected to this fraudlent practice from Xfinity?