Down/Up Speeds Sporadic

Current plan: 300/30
Modem: CM1000 (also using a separate wireless router)
Last tech visit: 2/28/25 (couldn't find issue on my end. speeds up/down normalized during his visit)

I'm in an apartment complex that includes basic Cox internet. I transferred my plan and pay an additional fee with TV.

The past two months I've averaged 30 down and 12-15 up.
I may get lucky and the bandwidth spikes to 300+ down and 30+ up, but it is just for a few minutes.
Doesn't matter if its day or night, weekday or weekend.
For work purposes, I've had to reduce the devices connected, because I no longer have the bandwidth available.
The tech that visited said my modem reads fine and everything looks good "on my end", but there could be issues elsewhere. I should wait to see if it works itself out. Well, it hasn't.
And, I'm now paying for speeds that I am not even close to hitting.
Should I call another tech out? What can I expect that tech to do?
This is frustrating.