While travelling by land across the brazilian/colombian border, my phone seemed to be roaming ok, picking up networks on both sides, receiving the "welcome to brazil/colombia" messages from my provider T-mobile uk. This happened several times as i was near the border for some time. But then when i flew to Bogota the phone refused to register with any network, even though it was able to detect a list of providers.
I have tried to fix it without luck so far, the message remains "Not registered on network". I spent an hour on the phone to T-mobile UK customer services, they could not help and passed me to Samsung. I tried a complete factory reset, still no luck. Samsung will only help when i return to the uk, but this won't be for 2 more months.
Any help or suggestions welcome. There is a lot from a google search, but seems to be fishing in the dark.