Samsung shop in Liverpool 1.
I doubt very much there are genuine ones out there..
Ive in the past ordered ones without the Samsung box, only to peel back the label to discover its a fake.
Watch out for phrases like "Genuine Replacement" which does not translate into a genuine battery.
I have found batteries and such in Samsung boxes have come back genuine. Google the battery and look for images of genuine packaging.
You may find after all that, its as cheap to invest in a new one.
Good luck on your quest