I placed an order and noticed that it still had my old address as the invoice address. Interestingly, the order seemed to have still gone through. I did change the delivery address to my work address, so it should still be all OK.
However, when I try to change my account/invoice address, it says that the details exist for another account already and to reset the password. It's a new build, so the address would not have been used by anyone else before. I did add it to my delivery address options and I tried removing it but I still get the same error.
Cheers.