This worked for me, my guess is it's only applicable if you've had an account a while and don't open emails as per the screenshot.
Hi I just used this code at 4.35 am on 28/05/2018 and it worked !!! I got 7.50 ish off my order thanks.
I've also been sent the same email with the same code and it doesn't work =s
Thanks anyway :)
I’m really sorry guys I thought with it being such a generic sounding code it would work. It worked for me, it must have been unique use!! I will try and delete