'Activation required' appears several times a day

Hi there,

Wonder if anyone can help me as i'm pulling my hair out!

The Message - 'Activation Required' appears on my iPhone Xs several times a day.

I have attached an example below..

Quite often after I dismiss the message, I get the following page -

When I swipe up, it just take my back to the main page or sometimes it will ask my to connect to wifi again, which I can just dismiss.

For context I had my iPhone on launch day, that message appeared on day one and every day since.

I have done the following -

• New sim card
• Factory reset
• Set up the phone as new
• Set up the phone from a icloud back up
• Set up the phone from itunes
• Set several diagnostic reports to Apple team.

I have a theory that when my phone picks up new masts (say when im travelling in my car) a problem occurs as I notice it often when i'm moving around. Also, if I look at old photos (stored in the cloud) on my phone the message will appear then. Having said that, I still get random 'activation required' messages when its just sat on the side.

Unfortunately, Apple after care has been really quite poor, i've been waiting over 2 months for an update, I don't get replies to my emails. My case was 'escalated' to the engineers about 6 weeks ago and as of yesterday the after sales team had not had an update...

If anyone out there can offer some advice I would really appreciate it.