Don't panic. Contact our BT One Phone helpdesk right away to report it. We're open 24/7. The number to use is 0845 154 8844 (or 8844 from a BT One Phone) and select the option for lost, stolen or replacement SIMs.
If your standard BT mobile phone has been lost, damaged, or stolen you need to contact us immediately. You'll find contact information on our help and support site.