on 02-08-2019 21:46
You could try by calling customer services Guide: How to find help & contact O2
but usually, you would need to take delivery of the phone and then return it under the 14 day change of mind policy.
OnePlus 6 (O2 & Sfr), Z3 Tablet (Three UK), iPhone 8+ (EE)
on 02-08-2019 21:47
You can't change it online
Best option call customer service in the morning