Continue having issue with my receiving all incoming calls since October 2024.

I have been continuously contacting TMobile in regard to not receiving some of my incoming calls since October. I have went thru all troubleshooting multiple times and as with Apple care.  I have paid my monthly bills and but getting the run around.  I have tried t speak with management but ones never available.  Now I’m contacting corporate with a complaint. I need this resolved but nothing is happening. I don’t want to switch my service to another provider all my business is tied to this phone, which I have missed business opportunities due to this issue. What can corp do to help me??????