You have to talk to someone in that town and give them a harbour mail. I don't know who exactly, try everyone.
To get a harbour mail... try that big big pokemart in Minamo city (is that the name?) and go to the level with the hearts on the walls... and save, then buy one item and use it and see if you get a Kyamome letter, if not, go back and try again...
Bah :X