Upgrade confusion

[Rich2]

I've recently upgraded. When my new phone came I put the old sim in it. Now there are two numbers on my bill.

[jonsie]

It sounds like you took out another contract rather than upgrading

Call O2 and ask them to migrate your old number to the new account which will end the old contract automatically

Guide: Coronavirus Community Help and Support 

Keep calling and choose any option @Rich2