Leigh forward Jamie Acton has said he is "sorry to let everyone down" after having his ban extended to four months.
The 25-year-old was suspended for nine games on Tuesday after admitting a charge of "other contrary behaviour" during the loss at Catalans on 1 July.
Acton appealed against the severity of the ban but his case was dismissed by a Rugby Football League tribunal.
He was charged after grabbing the injured Greg Bird's shirt, lifting him and pushing him back to the floor.
"I accept full responsibility for my actions and they weren't acceptable regardless of the grading I've been given," said Acton, who will now miss the rest of the season.
"I will continue to work hard and improve on the negative areas of my game and support the team as best I can off the field for the rest of the season and whilst I'm part of the club"
'People can make their own mind up'
Acton's ban has been back-dated to the day of the Grade F offence - the most serious on the RFL's disciplinary scale which carries a minimum ban of eight games - but its increased length means that he will now not be able to play again until next season.
Initially he would have been available for the last of Leigh's fixtures in the Qualifiers as they bid to retain their Super League status after winning promotion from the Championship last year.
"While Jamie's actions are completely unacceptable in our game and cannot be defended in any way, I do not feel that the grading imposed was appropriate," said Leigh owner Derek Beaumont.
"We consulted a barrister familiar with these situations, who also strongly believed that the grading was inappropriate.
"People can make their own mind up and we have to accept the decision now for what it is and I would like to thank all those people offering their messages of support.
"Jamie is under no illusions of the consequences of his actions. He has worked hard on his discipline, in particular the fighting and retaliation aspect, which he has completely eradicated from his game.
"I am therefore satisfied that he will learn from this and we will work with him to eradicate the stupid and potentially dangerous aspects of his game so he can reach his potential of representing his country in the near future."