Thanks for the help and diagram.
I pulled all the ULF, amp, harness, etc. out. Had a good look at all the conections to ensure no bent pins and reconnected it up on the floor of the boot. Added a temp earth to the ULF case and gave it another go. (after having charged the battery due to flattening it by leaving my interior lights on overnight and constanly cycling the engine without a charging run since last Friday...oops)
Bingo - we got pairing!! Recognised the Blackberry 8100 and could make and receive calls. Address book is still struggling, but that may be the database size and my lack of understanding of the controls (dark, raining, etc.)
Bimmernav seem to be redeeming themselves from sending the faulty pairing button and are very helpful by email and hopefully a new button is on the way.
Getting there....