If you're based in the UK, @sha9, I'd recommend contacting the Samsung Accounts Team on 0800 995 1079, as our colleagues will be able to assist you in getting your account details updated. This will help ensure that you can use the two-step verification as expected. 👍
If you happen to be based outside the UK, please reach out to a Support Team in your region, as you will be given the contact details for the Accounts Team that covers your area:
https://www.samsung.com/uk/function/ipredirection/ipredirectionLocalList/
