Siri stopped working/ bad signal

I have the iPhone 8 . 6 to 8 months after purchase I was having problems with receiving texts and phone calls. I was told Apple care would take care of my phone after two visits to the store and running all tests and apple support seeing I had no damage on my phone the third time in the store they gave me a new phone. Great problem solved. Then at 2 years when Apple coverage ran out I purchased monthly insurance. Now 2 and 1/2 years old I’m having issues with Siri, my phone burning up and shutting down. After 4 phone calls with Apple I went to T-Mobile for a warranty exchange. Between me on hold with Apple and T-Mobile being sent around to different departments at Apple we couldn’t show that Apple store had given me this phone. 3 hours and still Apple support hung up and had my phone number to call me back but did not. Apple support blames T-Mobile but they did not give me new phone Apple store did and no one updated the phone IMIE and T-Mobile provided the proof of purchase to Apple but Apple is not providing all the visits to the store and didn’t update the new phone so now the insurance Is having problems giving me a phone because they cannot see in records that my purchase at T-Mobile and the exchange of iPhone at Apple store. I’m still waiting to see if I can get a replacement! I really don’t understand and this should not be so complicated. I’m not asking for anything free. I’m not yelling or screaming. Has anyone else had these issues with Apple support and Apple care?

Yes my phone is up to date. I have done multiple trouble shooting with T-Mobile and Apple. No matter where I am at my sire starts talking then does one beep before a turn. My car was also tested for any Bluetooth problems . Nothing was wrong and no update on my car was needed. Any more suggestions. Open to anything! I’m very careful with my phone. So no damage physically or internal water damage.

I have called Apple twice and they really don’t know but we sent some tests they did on my phone to the engineering department. I’m expecting a call tomorrow from them. I was asked to perform some tests with my car and someone else iPhone and was asked if I could use someone else car and pair my phone and see how that works. At this point that’s really just asking way to much of me and someone else’s time. I have my fingers crossed and hopefully tomorrow I will have a better idea on how to fix. Not ready to buy a new phone that’s less than 3 years and always taken care of it. Wish me luck!