Sony Ericsson :: Spiro W810i Unable To Send Or Read SMS Messages?

About 2 weeks ago I purchased a new Spiro mobile phone. Apart from the occasional problem of the screen going black and restarting I didn't have any problems in particular.That is until this Saturday. I was having a discussion with a friend via sms. Everything was working fine until the phone stopped sending sms. It also hasn't been able to since then. I can normally write the message, and when I press Continue I normally go to the sending screen. However, when I press Send I return to the Messages screen and the message I just composed is nowhere to be found. Neither in Drafts nor in Sent. And of course it isn't sent to the receiver. As you can understand I am by no means able to send an sms message to anyone because of this. Along with this problem, since this Saturday any sms that I receive appear as blank when I open them in Inbox. As a result I can't read messages either (apart from the first words shown in the Inbox screen under the name) And that's it, I can neither send nor read sms messages with my Spiro. That makes my phone pretty much useless when it comes to messaging. I would very much appreciate any help or advice on how to fix this problem. I would also appreciate any information regarding the cause of this problem.I do not believe my network provider is responsible as my old phone (W810i) can normally send and receive sms messages.