Update...
I was able to remove the antenna this morning. I pulled down the headliner near the high level brake light and there is enough room to access the Telecom Box under the antenna. You need to release the clip that holds the TCB to the antenna. Once this is free, removing the T25 screw at the top will allow the antenna to be removed.
I've ordered a new antenna and also a new TC Battery. I've seen many cars recently have the 'Emergency call system not available' message. Mine being a 2018, I thought it would be best to change it too while I had access to it.
Part Numbers:
Antenna - 65209303037
TC Battery - 84102447710
I hope this fixes my issue!
