Gigabit service that isn't measuring up

I am so frustrated with the Gigabit Speed service. I have had 5 + service calls. On the last one the technician was able to get my cable modem to run at 1.1 GBPS, but only using his test equiptment and adapters.

I have recently installed an approved Docis 3.1 cable modem- (SB 8200).

Just upgraded ALL the house cabeling to Cat 7,

and now new routers that have Gigabit throughput. (ASUS AC2900 WiFi Dual-band Gigabit Wireless Router with 1.8GHz Dual-core Processor and AiProtection Network Security Powered by Trend Micro, AiMesh Whole Home WiFi System Compatible (RT-AC86U)).

Every change was recommended by the COX technicians. He could only get that speed (1.1) when talking to a fellow inside COX at the other end of the cable. I was seeing 860 MBPS on my equipment for a day. Now it is stable down at around 300 MBPS MAX. Lower on the weekends...about 95 MBPS today.

It sure seems as if I am going in circles with COX and the speed claims are a "bait and switch"?

Thoughts?

Ideas?

I am paying a lot of money for sub par access.

Every time they come out it is my systems fault....now there is nothing to change.