MIG wrote
[...]
I found that you can't claim a refund without registering with your
full name and address. In other words, if you've been caught in such
a situation, you have to choose between being ripped off for £8 and
having your movements tracked thereafter. Not good news if you prefer
not to register for the sake of privacy.

No, not "thereafter" since you can immediately turn in your card,
collect the deposit and get a new unregistered one.

Only your prior movements will thereafter be associated with you on Big
Brother Ken's database.

--
Mike D