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I do not think sony can do anything,you need to contact network operator.
If you bought it from Vodafone Ireland,they have the rights to change firmware according to their need.I suggest you contact xperia care and see if they can help you:
http://www.sonymobile.com/global-en/support/contact-us/
Buying from an operator it will be locked to their network - Pay a little more for Generic and or unlocked devices and you can use it on any network
1st you should check if your phone can be unlocked or is it permanently locked
Dial *#*#7378423#*#* then go to Service info then Sim lock and post results exactly as they are
I understand your concern, however, OEM make changes to the devices upon the destiny operator request and when you want to take the device which is brabded to another network, the original carrier/operator will give the code. Some of them will charge you depending on the contract.
Sony is out of the picture here even thou they make the devices. Get in touch with the old operator to get the code. This is the only way.
Do you get any x's between [ ]?