Hi
@Paula4109You need to contact customer services on 202 from your handset or 0344 809 0202 from any other phone, when asked about the purpose of your call, then say lost / stolen to get through to an agent.
You are only allowed one free number change, and you may be asked the reason for the request.
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iPhone 16 Pro Max - o2 and Spusu
Xperia 1V - Spusu
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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