How can I escalate my Apple Care complaint?

I am facing an issue with my Iphone within apple care.

The wifi stops for sometime for no reason. and resumes after 5 mins. at random times. Sometimes it happens 3-5 times a day to 10 times a day. on a good it could happen only once

Now apple care team said we fix only if we see the issue and I asked them to take the device and run proper diagnostics. they said no.

How do I complain furhter on this. Apple support wont help

And my money for apple care is useless.

The only option they gave is use this phone and tolerate the issue or buy a new phone.

Whats the point of having appleCare then.

This is so unfair and they dont even listen my concern anymore.

PS: I am connect to 8 Apple devices and only this phone has the issue when this issue happens I test next work on other devices and they all work fine

[Re-Titled by Moderator]