OK - Just to bump this back up as it is related.
I added a new contact to the phone and then joined it to their facebook account through the fb app (as the name is completely different).
This worked, but the phone was then displaying the Facebook name instead of the real name...so I thought I would delete the contact, create a new one with their facebook name...link the accounts and then rename the contact to the correct name...as with all my other contacts, the google name is the priority.
I did that and now cannot link the facebook contact anymore. It doesn't appear as a suggestion...and going in via the facebook app, pressing the profile pic no longer gives me any options.
I have now told facebook to sync all of my contacts to the phone (previously I had it set to only sync those that were already on the phone), but it resolutely refuses to bring this contact back to life.
Any ideas?
******EDIT*********
Never mind, I figured it out...had to remove the facebook account and re-add it. Bit of a pain in the backside...but at least I know now
