If you know you are served by a specific cabinet and there is not a new one next to it, then you wont get fibre. Depending upon where your parents are, even though they have a new cabinet next to theirs, it may not have been activated yet I guess (edit...just re-read your post and see this isnt the case). Are they Barnstaple or away? Also, which provider are you checking? I guess BT will give the quickest go live, whereas not all suppliers will be live straight away...you say BT and plusnet are active...are you checking their address /phone etc on bt or plusnet?
edit: another thought about your parents...the existing cab could be full? In which case they will need to wait until another one is installed (I think).
Glad I moved to BT early April.....my order is in and install date 20th May (although it was originally a week earlier), but even though BT site now saying AO, the talk talk site still says unavailable, so different suppliers will take longer to offer it, even on a live cab and live exchange.
Edited by deleted (Mon 29-Apr-13 20:54:56)