Vostro 7510, S2422HZ, USB-C, speaker screech sound

Hi, I have a brand new Vostro 7510 and new S2422HZ monitor, which I ordered after seeing a Dell ad for the Video Conferencing Monitor, where everything works via a single USB-C cable (camera, mic, speakers, extra ports).

From day 1, when powering on the laptop and monitor - and/or when the screen sleeps - and/or when waking from sleep - the speakers on the monitor will sometimes start screeching and squaking VERY LOUDLY until you either unplug the USB-C or power off. It doesn't happen every time, somewhat random, it's enough that you don't trust the computer and fear using it. This happens even if you disable the audio on the monitor in Windows Sound setting.

I have been through absolute heck (they won't let me post my real thoughts) with Dell support.

First they logged in to the screen and we uninstalled and reinstalled all of the various Realtek and MaxxAudio drivers, left it running and had the same results.

Then they asked me to factory reset from the local factory image, with the same results.

Then I did a factory reset this time choosing the option to download a fresh copy of Windows (it seems to be from Dell because it still has all of the Dell software). This time I was able to get it set up and run without immediate screeching, but the first time the monitors went to sleep, it started making the Windows notification sounds of devices connecting and disconnecting, non-stop... as if the monitor was sleeping and that registered as disconnect, but as the notification sound played, that reconnected it. It was schizophrenic madness - all happening while the screens were off. So I woke it up - and voila - LOUD SCREECHING sounds again.

I've now spent close to 40 hours troubleshooting a new Dell laptop and monitor. Every time I contact Dell, I have to start from the beginning. Yes, I'm using the supplied cable. No, I don't have other monitors or laptops to test on, I'm just the paying customer, not your test subject. Now they tell me it's too late to return it because it's been more than 30 days.

This is the worst purchase experience I can imagine from what is supposed to be a reputable company. I'm waiting for a call back from the Advance Resolution Department, but from what I've heard, they will just give me excuses and deny responsiblity. Does anyone have any advice? I'm so worn out and disappointed. Thanks.