Chosen Solution
Just heard back from an authorized Apple technician and he also agreed with what the geniusbar guys told me: an issue in the rear mic is a whole unit replacement i.e. £287
It is replaceable. The rear mic is located on the power/volume flex cable. The repair is a bit of a pain but take it slow, stay organized and you will be fine. [linked product missing or disabled: IF314-030-1]
