The 41 year-old Canberra man had been on NewStart for about 12 months while he got back on his feet after injury forced him out of the commercial painting industry in 2014.

But in October he received the letter, stating his reported income differed from Australian Taxation Office figures and he needed to repay $2,928.59 to Centrelink.

"During that time I took my long service leave," he said. "There was no way to declare it on the app, so I called up and was told not to worry about it. They are now telling me that was wrong."

Mr Moore had Centrelink dig up the conversation where that advice was given by customer service staff but for months since he has been trying to straighten out the robo-debt notice through a review process.

"It's on my mind all the time," he said. "I did the right thing and contacted them about my long service leave. I was someone who just needed help for one year after decades in the workforce. I did what they'd asked at the time. I can't pull the money out of nowhere now."

Watson resident Darci was gobsmacked after she received a $3,507.26 debt notice, but said she lost faith in the Department of Human Services' rigour when Centrelink revised the debt amount to $905.41 after a fact check.

The 32-year-old said it was plausible she had made an error during one pay period over the five months between 2013 and 2014 she received New Start.

But could not comprehend how the numbers run by the automated recovery system could be so inaccurate.

"My total payments would have been close to $4,000 or $4,500," she said. "There was no way I could have reported so badly that I owed back nearly the entire amount I was paid."

She is waiting on the outcome of a manual review by Centrelink but has been forced to make two $100 weekly repayments so far toward the unconfirmed debt amount.

Aidan was a Youth Allowance recipient for five months during his honours year at ANU in 2015 and was asked by Centrelink to clarify his income against Australian Taxation Office figures in December.

"The system distributed my annual income, as reported to the ATO, evenly over that period, rather than recognising that I had worked substantially reduced hours during the time that I was receiving assistance," he said.

The 25-year-old, who was found not to owe anything to Centrelink, said the large numbers of false and inaccurate debts being issued was largely to do with the system's "inability to recognise factors such as pay-per-period and business name differentiations."

Member for Fenner, Andrew Leigh said his office had been "inundated" with letters of angst, fear and frustration as more than 50 Canberrans contacted him about their Centrelink robo-debt woes so far this month.

The heartbreaking stories of financial stress and worry were a reminder of just how tough it was to get by on the poverty line and highlighted the "crude way this [process] was being carried out", with people who do and don't actually need to pay back money.

Dr Leigh has called for the immediate suspension of the Centrelink automatic debt identification system until its bugs are ironed out.

"If you have system that is mistakenly accusing someone of wrong doing one time in five, that is not good enough," he said.

He said as so many people affected had so little, it was vital such bungles didn't exacerbate financial hardship.

"Noone objects to the use of IT systems in identifying fraud but what this government has done is taken the human component out of that to create a robo-debt raising system that is generating huge angst across the Canberra community."

Darci and Aidan asked not to have their surnames used.