Cox neighborhood issues are a pain in the ass, but you are going from bad to even worse moving to cenlink.
You need to keep calling cox and escalating your call, get your trouble ticket number and keep calling. You are going to have to repeat yourself many, many times but once you get to the higher tier they will start doing monitoring on your line from the NOC and start a chain of diagnostics.
You have to remember, the reason why 99% of the time you have to deal with the line readers at tier 1 support is because people dont have their shit plugged in, they have broken computers or otherwise have something else stupid.
Something else to think about is the temps this week have been higher then normal, how is your cable routing from the cox box on your wall to the inside? Is the cabling running outside on a south wall? etc.
Ive been on cox at five different addresses, three different business accounts and use their highest tier for 15 years. It may be a shit sandwich some times but there is nothing really better in the valley (when it works.)