How to change Upgrade decision?

[BigDaddyUK]

How can I change my choice? If I chose Upgrade to Samsung Galaxy S20 Ultra 128GB and I want to change to Samsung Galaxy S20 Ultra 512GB...

[jonsie · Accepted solution]

You need to speak to customer service

Guide: How to find help & contact O2 

Otherwise you will have to wait until the phone is delivered and then return it under the 4 day change of mind period.