While Mara Branco was attempting to sort out the situation, Paychex told her that there was no option to bring her husband's insurance payments up to date, and that the company was instructed by Russell Reid not to accept any more payments from the Brancos, she said.
"[Paychex] said the only way we can accept payment is if the employer tells us that we can," she said. "They said there was a note on my account not to take payment."
The Brancos didn't even receive notification of cancellation of their policy until the beginning of July, she added.
"They canceled my policy on May 5, and I didn't get the letter to July 2," Mara Branco said.
After that, Paychex returned the $518 payment.
When contacted by ABCNews.com, Paychex spokeswoman Laura Saxby Lynch denied that Branco's insurance was canceled over a 26-cent underpayment, but added she could not discuss the situation further.
"There are more facts related to the story and the process that I can't get into because of pending litigation," she said.
Lynch also would not comment on whether or not the payment was returned to the Brancos.
Mara told ABCNews.com that although she has a lawyer, she has not filed any lawsuits against Paychex or Russell Reid.
A representative from the DOL told ABCNews.com that it is their policy not to confirm or deny the existence of investigations.
Calls placed to Russell Reid by ABCNews.com seeking comment were not returned.
Mara Branco soon decided to contact the federal Department of Labor (DOL) about what was happening. She said that the DOL repeatedly contacted Russell Reid, but was given the run-around.
She said that it took multiple calls from the DOL to Russell Reid, and in total, three weeks since she initially contacted the DOL to resolve the situation.
"Every time they tried to contact Russell Reid, it was never OK," Mara Branco said. "It took the federal government a lot to get me restored."
On Monday, a check for Sergio Branco's insurance payments for the past few months was finally accepted by Paychex, which confirmed with ABCNews.com that his policy is back in effect.
"Mr. Branco was fully reinstated and successfully enrolled in coverage on Monday," Lynch said.
Sergio Branco's transplant has been pushed back from Aug. 16 because he must meet with a doctor in New York this week to undergo some tests. On Monday, the couple should find out when he will have surgery.
For Mara Branco, who is juggling three kids, a sick husband and an insurance nightmare, the situation has been "agony."
"I'm sure there are other people in the same situation that I was," she said. "You have to be very strong-minded to get things done."