iPhone Experts - help!

So, a few years ago I passed my old iPhone to my wife ( as you do ) - she retained my original iTunes profile and renamed the phone. I then upgraded her old phone to a newer model earlier this year and all was tickets-boo.
I used the company's freebie.

Enter Autumn 2019 and I've purchased the 11 and registered it with my credentials.

I've tried to "disassociate" the wife's phone from my iTunes account, including setting up her own iTunes and iCloud shit.
This is where it gets arsey - her phone won't recognise her "new" account and is now trying to take control of my fcuking new 11.

Tell me, Experts, what I've done wrong and what I now need to do to unravel this ungodly flaming mess.

Maybe

https://support.apple.com/en-us/HT204074


Remove your associated devices

On the Manage Devices page, click Remove to the right of the device that you want to remove. Depending on when you associated your device with your Apple ID, you might need to wait up to 90 days to associate the device with another Apple ID.

If you can't click Remove (the button is dimmed), the device that you're trying to remove is connected to your Apple ID. Sign out of the iTunes Store on that device, then try again to remove it.

Smogbob said:

Maybe

Click to expand...

Actually, I think you've hit the nail on the head for me there. I owe you a beer, Smogbob.

If you can’t sort it, pop into the apple shop and speak to one of the tame geeks.
They’ll sort it for you.

AberdeenAngus said:

If you can’t sort it, pop into the apple shop and speak to one of the tame geeks.
They’ll sort it for you.

Click to expand...

Now, you're after a pint of Tennants, too......
Cheers for the input.

Been though almost exactly this. One other thing otherwise it all keeps coming back is that any Apps on your wife’s phone downloaded using your iTunes or Apple IDs need to be deleted and reinstalled using your wife’s new accounts.