Is this a provider or phone issue?
Right now I'm using Orange-Israel.
Seems crazy though that they can change the language when you get voice mail to a different language but not the written messages from them (Orange-Israel).
Orange did manage to change GPS to English.
When I'm back in the UK and use Orange-UK it will be interesting to see what happens.
If somebody buys a phone in Thailand, a lot of the aps and messages from the provider would then be in Thai?