iPhone X EXCESSIVE data usage

This is my second IPhone X. The first one burned through 18GB of data in 5days. My plan is 10, with 4 bonus gig, which IVE NEVER EVER FONE OVER...

Just got home from the apple store with my NEW PHONE.

WiFi connected

WiFi assist off.

Fb messenger has used 9.2KB while on WiFi, with WiFi assist OFF. It’s the only app that has eaten data.

In 5 mins system services has used 799kb. In 2 hours it used an additional 3gig. I’m not even on the darn thing. It’s sitting on my counter! Verizon tech working with me is at a loss. Gave me open data to try and work through it. Apple store? They haven’t a clue what to do either. I’ve shut off all non essential apps for cellular. I feel like I’m back using a Motorola Star TAC. This phone is just burning data like it is a tinder box. Tech support? I’ve been on the phone with them every night this week. All say the same:

Network setting reset

Erase, reformat, back up from iCloud

Erase, reformat, use as new phone.

All ends up burning data. Apple, I expected more. Really. when I buy apple, I expect it to work WITH OUT issue. Someone is rolling in his grave.

Anyone have any solutions since the Apple is completely unaware there is an issue here? Even a simple google search shows that it’s not just me!