If you lose your SIM card holder, contact a Sony Mobile contact center.
Do not attempt in any circumstances to insert the SIM card into your device without the SIM card holder. Inserting the SIM card into the device without the SIM card holder could damage your SIM card or your device. Sony Mobile does not warrant and will not be responsible for any damage caused by such action.
To get contact details for your nearest Sony Mobile contact center, go to http://support.sonymobile.com/global-en/contactUs/