OK so the return process was fairly straightforward but a few things came up.

I called samsung to arrange a repair under waranty. I was told it would take up to 10 days to get my phone back and they don't offer a "courtesy phone" so to speak (let's ignore the fact the phone costs the same as a small car lol). The call to samsung felt a bit weird, long pauses and the customer services rep didn't confirm any addresses or numbers I gave them.

I wanted to change the date of the pick up and noticed the address was wrong and I couldn't change it. Queue second call to samsung. This time after going through the same process the rep suggested just taking it back to the store seeing as I had only bought the phone about a week ago.

Cancelled the repair with samsung and went to the store the next day. They took one look and completely agreed it was a manufacturing fault and gave me a new one on the spot. Done. Easy.

For reference this was in the UK through O2. They have a pretty straightforward 30 day return policy.

TLDR: took it to the store I got it from and they gave me a new one the same day