The price tag to fix the federal government's new payroll system has jumped by as much as $10 million in the past month, with Public Works Minister Judy Foote saying the cost has now reached $25 million.

"As you've heard me say before, I'm not focused on savings here ... I'm really interested in solving and fixing Phoenix, and we're going to do whatever we have to do to do that," Foote said.

The new information emerged after Foote met with union leaders on Friday to discuss the government's troubled computerized pay program called Phoenix.

Since the system was rolled out earlier this year, more than 80,000 public servants have experienced pay problems.

Foote used the meetings to assure union representatives that the government is still on track to clear the backlog of issues by the end of October.

"As far as I'm being told, at this point in time, it is a firm deadline," Foote said.

The Public Service Alliance of Canada, one of the largest unions representing public servants, has openly doubted the government's ability to meet that deadline.

PSAC's national president asked the minister for a warning if there's a chance the deadline could be pushed ahead.

"I did stress to them that it would be appropriate, if they weren't going to make that target, to make it known sooner," Robyn Benson said.

"Because there's nothing worse than saying you're going to hit a target, not hit it, and then have to back-pedal afterwards."

Additional apology

Foote has also agreed to issue another apology for the Phoenix fiasco, this time in writing — something PSAC had asked for.

"I have already said I would apologize to anybody who is suffering hardship as a result of Phoenix," Foote said. "I have no problem at all putting an apology in writing," Foote said.

The memo will also contain specific information about how workers affected by the pay system can access financial help.

PSAC says Public Works has also agreed to create a new committee that will try to answer key questions, such as "What's happened in the rolling out of Phoenix? What still needs to happen? How can we assist our members and their employees to ensure they can get money to buy groceries?" Benson said.

Performance pay questions linger

PSAC also questioned Foote about bonuses for executives in charge of rolling out Phoenix.

CBC News has confirmed managers were promised performance pay if they hit key objectives, including keeping the project on schedule.

Public Services and Procurement Canada says no executive performance pay has been handed out for 2015-16.

The information has prompted questions from the NDP about whether performance pay was a motivation for managers to roll the system out even if it wasn't ready.

"That's not my understanding," Foote said. "Of course, I don't know because I wasn't there in terms of the actual time frame of when it was supposed to be rolled out."

When Benson asked about bonuses, she said, "There was not a clear answer."

"She [Foote] didn't answer, her deputy minister avoided it, if you will," Benson added.

Foote told reporters the issue rests with the previous Conservative government.