Here is a minor contribution.
First remove the plastic wheel well by removing the 8mm head bolts so you can reach in and work on the antenna.
Remove the 10mm head plastic nut holding the mounting bracket to the inside of the fender
Remove the chrome nut on the outside of the fender which holds the antenna, retain the nut and plastic bits.
Let the unit hang loose in the wheel well.
Pull the deck out and disconnect the antenna.
Use plastic tube or rubber hose, insert the plug pin into the hose or tube and tape it well.
Pull antenna cable through the firewall by gently pulling and pushing with the tube until it is through
Remove old antenna and retain the serrated gripper bit and bracket.
Use the retained bits to install the new antenna.
Stretch the firewall grommet on the new cable, tape the plug to the tube and pull and push the cable through.
This way is easier than Bentley.