The combative midfielder has been left out of the national squad for their World Cup qualifiers and is now facing the end of his involvement with both club and country, leaving him to concentrate solely on finding a new club.
"I can honestly say I don't know what's happened. Since playing against Costa Rica in June I've heard nothing from my national team,” said Acuna.
"I'm surprised because I wanted to play in all Chile's World Cup qualifiers and worked hard once I was fit again in pre-season to prepare for them.
"I thought I would be called up for the match against China in August but I wasn't. I still thought I'd get the call against Argentina and Peru, but I didn't.
"(Juvenal) Olmos has talked about picking people who are playing regularly for their clubs and I think that's what is counting against me.
"But then there are others who aren't playing for their clubs, haven't played for six months or don't even have a club, who are in the squad.
"I'm not one to over-dramatise things but that hurts. I just have to accept I'm no longer important to Chile. Now I will concern myself only with my club and my future."