@MM5You would need to pay off the remaining device plan and then upgrade, once you have done this, then you can trade your phone in with the likes of o2 Recycle or Music Magpie and get some of that cost back.
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iPhone 16 Pro Max - o2 and Spusu
Galaxy Z Fold 6 - Mozillion
iPad Pro 11 M4 - Three
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This is not customer services and we dont have access to your account
I do not work for o2 or any VMo2 /Telefonica/Liberty Global Company