Some Trace Adkins fans are pissed ... bitching that Trace ruined their country cruise by jumping ship in Jamaica ... and all they got in return were concert tix.
We broke the story ... Trace got into a nuclear argument with an impersonator on board the ship ... and left the big boat for rehab.
Passengers feel ... cruise officials lied to them and said Trace left for a family emergency -- and tried to placate them with an hour-long open bar.
One woman posted on Facebook, "[Trace] gets shipped off and we get replaced by an hr of free sh**ty watered down well drinks for one hour ... What a JOKE!"
We're told ... Trace's camp is now trying to make good by offering passengers free tickets and a meet-and-greet at a future concert. For some fans, it's awesome.
But others -- who paid thousands to go on the cruise -- say they can't collect ... because they came from faraway places -- even foreign countries.
FYI ... the free tix don't come with an all-you-can-eat buffet.