In the midst of a campaign to organize Mercedes-Benz’s Tuscaloosa County auto plant, workers have filed charges of anti-union activity against them with the National Labor Relations Board.

The charges were not immediately viewable on the NLRB website, but according to a news release issued Tuesday, the workers claim retaliatory discipline for union activity and termination, as well as mandatory meetings where workers were made to watch videos with anti-union messages.

The United Auto Workers last month announced that more than half of the employees at Mercedes-Benz’s Vance plant have signed union authorization cards.

Attempts to contact Mercedes-Benz for comment were not immediately successful.

Lakeisha Carter, an employee at the Bibb County battery plant, said she has put in paperwork with the Family and Medical Leave Act “multiple times,” only to be told the paperwork was lost.

“I’m an outspoken union supporter and Mercedes illegally disciplined me for medical absences that were clearly covered by my FMLA requests. It’s just plain retaliation from Mercedes, but I’m not going to be intimidated,” Carter said in a news release.

Another union supporter at the battery plant, Al Ezell, said he was given permission to have his phone on the factory floor in the event that his doctor called him about refilling his prescription. Ezell has stage 4 lung cancer, according to a news release.

Ezell said he was still disciplined for having his phone on the floor as part of the plant’s zero tolerance policy, which he said he was unaware of.

Another worker, Taylor Snipes, said he was fired for having his phone on the factory floor, despite being given permission in order to be in contact with his child’s daycare.

He said the action came after he spoke up about being made to attend meetings to watch “anti-union videos that are full of lies,” he said in a news release.

“During the meeting, I told management that it was suspicious that I was being called into the office on the same day that I spoke up in anti-union meeting,” Snipes said. “My manager said the two had nothing to do with one another, but then proceeded to aggressively interrogate me about why I support having a union.”

Mercedes-Benz, along with Hyundai’s Montgomery plant, are part of an ongoing campaign by the auto union to organize in Southern plants historically resistant to organizing. According to the union, more than 10,000 workers have signed union cards just this year.

On Monday, a union vote was scheduled for April 17 through 19 at Volkswagen’s Chattanooga plant, encompassing the factory’s 4,000 workers. Earlier this month, the union announced more than 70% of the plant’s workers had signed union cards, petitioning for an election.