Sudden loss of signal after 3 years of flawless service.

Have had a 3 TMobile phones with unlimited data for 2 years. Data on all 3 phones was always nearly flawless at home, even with a max 2 bars!  Started to get a little spotty here the last couple of months, (today being October 24, 2022). About 9 days ago my data became nonexistent at my home, (nearly total for my phone service too). I called 4 days into it and they told me there was no tower down, then changed the tune and said they were working on a tower & to wait 3 days. However, between 10pm & midnight, the service picks up. I have a feeling they oversold bandwidth and are making excuses.  
someone suggested making a complaint with the FCC. I think I'll give them a couple more days after my service period starts over and if it's still slow, I will call again. If they don't resolve it, I will make that complaint to the FCC.