Bluetooth iPhone

When I use the voice recognition feature on the iPhone, linked through the Corolla Bluetooth, it doesn't recognize and hardly picks up my voice. It seems to be a volume issue but even if I scream it often doesn't come through and spell out correctly in texts, web searches, note dictations, etc. I've also noticed people are having a harder and harder time hearing me on phone calls. I reset the connection from both ends, reset the audio system, adjusted volume, went through the voice training feature, etc. Does this mean the Bluetooth microphone is going bad? Or is there a setting or compatibility issue? I have an iPhone 8 and the Corolla is a 2014 LE Eco model bought in fall of 2013 - the first one the dealer sold when the redesign was released that year. Any help or advice is appreciated, it is very frustrating...
Well, you should visit a service center and I am sure you will fix your problem there, but who knows how much it will cost, that is why first of all try to identify the problem. Actually it is pretty easy, just connect another phone to your car, and watch how it works. If nothing changes, then the problem is in your car. Visit the service, and they will easily change your mic or some wires that connect the mic to the computer. I had a similar problem some time ago when I dropped my iPhone, but in this situation died not the mic from my car, but the phone mic. I wanted to change it, but happily, I found a cool offer on and I decided that it would be better for me to sell it.