Internet speed SLOW...A MESS!

Hello. I have Extreme internet pkg. Should be getting 400 mbps or close on the Download and 20 mbps or close on Upload. My speed has averaged 20 mbps on Download and 11 mbps on Upload. Called Comcast last weekend and on the phone for over an hour as they remotely checked equipment. Tech was very good. In the end, scheduled for a person to come out to the house, check and possibly rewire the Wi-Fi since the original wiring was from 2004 and the thinking was the the wiring could not handle the faster speeds of present. Technician came to house yesterday, 3/16/21 and tested. He then ran new wiring. We could not connect to Wi-Fi at all, but could with ethernet. HOWEVER, even plugged in the download was maybe in 30 mbps and the download was worse than before with 2-3 mbps. He had no other solutions except that the router could be the issue and suggested I try purchasing a new one. He also said he would have the "bucket guys" come out with the truck and check some poles in my yard.  Thinking on the age of my modem and router, I realized that yes it is probably the router as it was about 8 years old.  (My modem is Netgear CM1000 Wireless modem and is 2 maybe three years old.)  So... I go and purchase the Netgear Nighthawk AC2300 Smart Wi-Fi Router....$210 worth.  Bring it home, do all necessary things and finally I am connected to my Wi-Fi...I was elated.  I did a speedtest and the elation was gone. Download, though better was only 130 mbps and here is the kicker my Upload...which I desperately need to be the best it can be...went from 11 mbps to 2 mbps.  So, back on with Comcast phone techs last night. I was connected to someone who even though had all the notes from last weeks phone call and the tech visit from the day, started from beginning checking my modem etc....then my speedtest dropped back to 20-30 mbps on Download and the upload stayed at 2-3 mbps. During the call, the call was dropped three times. It was coming from the Philippines. The technician reached out to me twice and the calls dropped again. I then called back and established a connection with another person in Philippines and that call was dropped twice as well. That particular technician mentioned that my modem may need a firmware update and gave me NetGear's # to call, which I did and ended up spending $130 for a years extension that would cover all of my Netgear products. I HAD to take it as it was the only way they would see if I needed a firmware update on my modem.  Needless to say while on the phone with them the call dropped before they could check.  At 1:30 in the morning, I was miserable and so disappointed and frustrated.

Here is where I am on March 17, 2021 as I am paying for service that I am not getting and don't know where to turn: 

• Current Download 46.53 mbps (plan is for 400 mbps) and 3.32 mbps on upload (plan calls for 20 mbps)
• I'm using a NetGear CM1000 Wireless Modem (DOCSIS 3.0 - 32 DS 8 US and DOC SIS 3.1 - 2 DS 2 US) that is 2-3 yrs old
• I'm using a NetGear Night Hawk AC2300 Smart Wi-Fi Router (purchased 3/16/21)
• Only one device is accessing the internet at once. I have a smartphone, Chromebook and Mac desktop 2013
• Have no idea if the bucket boys came to the house yesterday as scheduled as the phone technician couldn't seem to tell me
• If buying a new modem would do the trick I would go right now to get it, but don't want to spend another $200 and get the same service, PLUS since the phone call with NetGear dropped (and I paid the $130 for the GearHead service)  I need to call them to see if a firmware update on the modem will take care of the problem before buying a new one
• I am desperate to get this fixed: 1) I am paying for Extreme and not getting the service paid for and 2) I am involved in many Zooms that provide personal enjoyment such as book studies or bible studies and would like to be able to continue and 3) and most importantly, I do content creation, course creation that I stream and I create videos for delivery and I need to have the best and consistent network speed that I can count on. 

I would appreciate assessment on the situation while I go ahead and make contact with NetGear about possibly needing the firmware update on the modem.  Isn't there anyone higher up that provides technical assistance other than the phone technicians?  I feel like I am swimming in the middle of the ocean right now and do not know which way to turn for fear of just getting the same "well let's check your modem, let's restart your computer"....  Any and all help, suggestions would be greatly, greatly appreciated. I have been with Comcast for 37 years and have had wi-fi since 2004.