I've just spoken to BMW Assist on 0800 561 0555
They confirmed that 'BMW Assist' and 'BMW Online' are now combined as 'BMW Connected Drive' and that the service was free for 3 years for 'all new accounts from 1st Sept 07'.
She confirmed that as I had not registered for the 6 month trial, my account had never been activated and I was eligable for the 3 year offer. I am not sure what the situation would be for those who already pay for BMW Assist or are on the 6 month trial.
I downloaded the form from here:
It doesn't mention 'connected drive' and the lady I spoke with told me just to tick 'BMW Assist'.
I guess I now wait to hear back from them.
Lots of info in this video: