You're better of asking in the Official Sony Mobile forum (link) as I'm sure they be able to help..
However I have found the following which may be of interest..
The Ice Cream Sandwich software update for Xperia™ S is now being rolled out. The update is released in batches, and below you will find links your phones list of all the currently released ICS software’s. Since there are minor differences in the software depending on product, country and operator we have a unique identifier that we call Sales Item (SI). The SI is identified by an 8-digit number in the format XXXX-XXXX. To find out what SI number your phone has, please take off the back-cover and check on your label.
We suggest that you use the in-page search in your web browser, which is commonly found by pressing ctrl + f key on your computer’s keyboard.
If you find your SI in the released software table the software for your device is released and available in PC Companion and Bridge for Mac where you can update your Xperia™ S. If you have enabled notifications for software update you will receive a notification about the ICS update in your phone. You can make the update and change settings for notifications in the Update Center application found in your app drawer.
The update will be directly accessible in your phone over mobile networks and WiFi, but also with the option of upgrading using a computer – either with our web-based Xperia Update, PC Companion or Bridge for Mac.