BOSTON (CBS) – Sheila O’Malley of Charlestown couldn’t believe it when she opened her paycheck from her seasonal job at UPS. “I was shocked,” she told the I-Team. She worked 41 hours that week, many of them during the overnight, and ended up with just $14.52.

Sheila assumed it was a mistake and the money would be refunded. In part, because Sheila, like other thousands of other seasonal part time UPS workers, signed an agreement to pay the $500 Teamsters union initiation fee in $32.00 weekly installments. But UPS told her it wasn’t a mistake. A spokesperson for UPS told the I-Team, “Local 25 reversed this long standing practice by rescinding this policy.”

For the new hires, that meant the balance of the union initiation fees and dues would be deducted in one lump sum. For Sheila, that was $490.00- nearly her entire week’s pay.

“I cried and tried to plead my case with them. But there was no wiggle room. He [union representative] said ‘You’re a part of the union now and you won’t have to worry about that coming out of your check,’” she said.

Some employees tell WBZ the union blamed UPS for what happened. But all of this finger pointing doesn’t matter to Sheila and the thousands of others who were left with little or no money.

“Financially it was crippling. It seemed like a few hundred dollars but that money was already spent and then we didn’t have it,” she said.

The I-Team has learned the National Labor Relations Board is now investigating charges of unfair labor practices against the Teamsters Local 25.

According to employment attorney Sol Cohen, it is possible the union may have violated federal regulations. “I would hope the union would take a look at this policy and reverse it and allow employees to go back on a regular payment plan,” he said.

Sheila says she thought the union was there to make sure UPS employees got paid a fair wage for the work they perform, telling WBZ, “I thought they were supposed to protect our rights.” In this case, Sheila says she didn’t feel protected and didn’t think what happened was right.

UPS says the union reinstated the payment plan after it collected all of the fees and dues. Because of the pending NLRB cases, the Teamsters had no comment.