ONE (1) Single Channel is FUBAR?!

WDAM-7,    digital 7.1 local outta Hattiesburg/Laurel, is the ONLY CHANNEL with audio the consistency of chopped liver, and video the texture of gravel....pixellated for days on end; LITERALLY, FOR A WEEK, SINCE the Kentucky Derby broadcast.  Every other channel via Roku Express and a JVC Roku box, is beautifully pristine.   Clue me!  I contacted DAM-7 newsroom, and griped about not being able to view severe weather live cut-ins to keep track of local Tornado warnings.   SOMEBODY needs to light a fire under these guys' rear-ends until this digital signal is cleaned up! I have restarted my entire Roku rig 3x this week!!!!