[mothered]

So, here goes a long overdue update:

Complaining with amz reps about the police report was going nowhere so I gave up on that approach a decided to go for the sealed box method.  I was aware it would be a bit risky and suspicious because of all the situation but I decided to go for it.
I contacted a rep again and said my account had been accessed by a flatmate when I was away and that he made the unauthorised purchase.
I requested the return and he gave me a label.
After a longer than usual amount of time and some more pressing they finally issued the refund.

Excellent.

You did very well with your approach and methodology, which was ultimately responsible for the SE's success.

Once again thanks for all your assistance and help.

You're most welcome.