@Anonymous What security questions couldn't you answer because you didn't have the phone?
@Anonymousis this any help to you https://community.o2.co.uk/t5/Other-Products-and-Services/Lost-or-Stolen-O2-Device-How-to-Report-it/ba-p/1023988
various ways of sorting this in the guide....
@Anonymousfollow the information in the links on Lost and stolen devices posted above....
Sorry, but I'm not buying that they would ask for the number of the SIM on a lost phone.
The date of the last top up would be an approx date and you should know the amount. Do you remember the security details? Have you registered for My O2? Most of the information you require would be there.
Hello @Anonymous! Sorry to hear you've lost your phone. 
Did any of the suggestions above help you out with this? Let us know how you're getting on!
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