on 02-01-2013 20:16
OnePlus 6 (O2 & Sfr), Z3 Tablet (Three UK), iPhone 8+ (EE)
on 02-01-2013 20:17
There may be an app you can use, but if this is a serious problem and you don't mind involving the police have a look here:
O2 will allow you one free number change.
Sky Unlimited Broadband - Windows 10 - Nexus 4 Android 5.1.1