Tech swapped my dying modem for new xb8, doesn't show in app, runs way slower

The new modem was swapped in after a week of running at slow (30mbps) speeds on my 1200mbps plan.  He complained about everything and finally swapped it out getting things working again at slower speeds... he implied I never got the full speed before which is a lie.  It worked fine for years.  The modem wasn't showing in the app so he said it "would take an hour" which sounded like [Edited: Language] and was. It still doesn't show... after somehow getting to support they didn't help either (are fixing registration on the backend) after another "oh let me get off this chat, it will just take a few hours" ... of course nothing.  This means I can't add back my pods so my network is still hampered after over a week.  Also checked and the credits they promised are nowhere. Can someone actually resolve this?  I see this xb8 issue has been around for years now.  I have spent an inordinate amount of time on this so far.  Help please!