Well what an absolute horrendous job to do, i can see now why they did a bodge job.
Only joking it took all of 5 mins and if the headlining had not been pulled away from the windscreen to start with i would still have it fixed in place
Remove the holding brackets for the sun visors in the centre of the headlining ( 1 very small torx head screw for each), gently prise the headlining above the rear view mirror away from the windscreen to allow a little extra vision through the 2 holes vacated by the brackets.Use one of the holes for access, lots of room

One 8mm retaining nut is removed from inside and the aerial base is removed from the outside.
Place new base into locating holes, refit retaining nut and brackets, job done
