See help here
https://community.o2.co.uk/t5/Pay-Monthly-and-Pay-Go/Cancelling-Your-Contract-A-Guide/m-p/566774/hig...Cost will depend on type of contract and length of time remaining.
If refresh you just need to pay off device.
If a standard contract it's the number of months remaining multiplied by your monthly payment.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion.
This is not Customer Service so we are unable to help with account specific issues.Currently using:
Pixel 7a (O2 & Lyca), One Plus 6 (Sfr), iPhone 12 Pro Max (Vodafone)