Mobile phone problems (Riga)

I have an LMT number in Latvia. It can accept voicemail but not text/SMS messages from the UK "3" network. It looks like the messages are being sent, but not received by LMT. LMT say they have an agreemet with "3" and there's nothing they can do.

Has anyone had similar problems? Last time I left a friend waiting for over an hour as I didn't receive his message!!

Thanks
Adrian