Gigablast barely reaching 550mbps after multiple tech support appointments and several different answers

I've scanned this message board for solutions not finding any so decided to post after my tech support appointment today.

I've been paying for Gigablast service for the last 12 months, when it was initially activated speedtest were reaching up to 940 - 1.2gs speeds wired and up to 800mbps wireless.  I have an Arris SB8200 and the Netgear Nighthawk X6 router. My home equipment includes two top of the line Alienware gaming devices, smart tvs, a 2019 macbook pro, ps4 pro and various android and apple devices that have gigabit ethernet wired connections when needed. So my equipment is up to par and not outdated.    When Covid-19 hit I noticed slower speeds and let it go due to the pandemic for several months until late June when I started running speedtest and became furious that the speeds were running 150-300mbps. So I setup the first tech support appointment and magically the morning of the appointment the speeds were up to 400 - 500mbps that morning.  The first tech ran test from my router and modem and and found my equipment was excellent. He went back outside and found some issues with their control box that needed to be updated by the higher level "maintenance" department.  Before leaving he claimed said he placed that order and it would take a few weeks to be completed. 

The slow speeds continued for the next 3 weeks so I decided to call tech support back for an update on the higher level "maintenance" department order the tech claimed he placed.  The call center agent told me the tech never entered any notes about an higher level "maintenance" order or any notes for that matter so they scheduled another tech to come out days later.  The next tech told me I never should have been sold gigablast because it's not reliable in this area yet?  I told him before Covid-19 we were getting  940mbps - 1.2gs speeds which surprised him.  He offered no solution and said that the issue outside needed to analyzed by a higher level tech and that I would receive a call to schedule that a appointment.  That never happened after a few weeks so I called and scheduled another appointment and since then another 4 technicians have been out.   The senior tech's that came out used a handheld testing device that showed a connection speed of 1.2gs but none of my devices could reach over 400-500mbps, he tried to blame my Arris SB8200 and the Netgear Nighthawk X6 router over the Cox branded router but when he ran a direct line from my router to the testing device it showed the same 1.2gs but only 400-500mbps wired, one at a time to my Alienware tower, gaming laptop and the same on the PS4 and 2019 macbook pro and android devices.  Nothing is wrong with any of my equipment,  so he he had no fix and the funny thing about it is when he left my residence he accidentally disconnected the tv line to our bedroom so another tech had to return to re-connect that line. That tech told me I could pick up a new wireless set top box from the Cox store which would give us freedom to move the box around the house.  So as a last ditch, I stopped back in to the Cox store to pick up the Cox branded modem to test and the wireless set top box, only to find out they are a package deal and can't be used with the equipment I own.  Was disappointment at the bad information from the tech on the wireless box but I still took home the Cox panoramic combo modem router to test vs my equipment.  The wired speed test results were the same at 400-500mbps on the Cox combo modem router just as I suspected.  I tested several devices one at a time with nothing else running... the speeds were that same as my Arris SB8200 and the Netgear Nighthawk X6.  So I returned the Cox panoramic combo the same day.  The Cox store employee told me he scheduled a higher level tech appointment that I didn't need to be home for and had to do with everything outside... another month passed by so I checked back in at the Cox store to follow up and was told by a different rep that no notes existed about a higher level appointment, I pulled out the business card of the other rep and said this is who helped me, he was off that day, so the other rep says he would have the other rep call me on the status of the  higher level appointment...  instead of that call, a few days ago I received a random email notification to confirm a tech appointment for 10AM - 12PM on a day and time I was not available....   after another not so happy trip to the Cox store, I agreed to another tech appointment today...

The results were the same, the tech's testing device it showed the same 1.2gs when plugged into my Nighthawk X6 or my modem alone,  but when I connect any of my devices the wired speeds range from 400-500mbps on any speedtest site and the funny thing about the speedtest sites, if we choose the closest Cox server here the speeds runs even slower at 120 - 400mbps so something is also wrong with the Cox speed test server in this area too...  I have up to date top of the line devices that were capable of getting 940 - 1.2gs speeds before something got slowed down by Cox in this area... but after searching this message board, I realize I am not the only one...

Any help or ideas would be appreciated... I will probably downgrade as gigablast seems to be a gigafruad...  sorry for the long post super long post, really frustrated after paying for something that doesn't work