All finally sorted for me. BW Customer Services have actually been great! They've upgraded my account to Diamond Select (via a status match) and corrected the format of my name (i.e. <Title> <First_Name> <Last_Name>) and fixed my email address after the hotel messed this up!

Finally, the hotel credited me the points for my previous three weeks of stays.

I have a few more weeks of stays booked so may end up with enough points for a weekend stay somewhere in the world.