Mr Wilkie has asked the Ombudsman to investigate how bank statements are used when calculating a welfare recipient's earnings, whether communication from Centrelink is easy to understand and how the system deals with one employer reported multiple times.

While Department of Human Services spokesman Hank Jongen has confirmed that the Ombudsman currently has 37 open requests for information for Centrelink investigations, the Ombudsman's office said complaints about the agency dropped in the three months since it released a major report into the debt recovery program in April last year.

It's not clear how many of the complaints about Centrelink are about the debt recovery program specifically.

The Ombudsman's office said it received a spike in complaints about the system in the six months before it handed down a review into the debt recovery system as a whole in April last year, but in the three months since those numbers dropped.

Between January 1 and March 31 last year, the ombudsman received 3,498 complaints about Centrelink, and between April 1 and June 30, 2503 complaints were received. The rate of complaints "remained relatively consistent for the rest of 2017," a spokeswoman said. The number of complaints for the full calendar year wont be made available until the Ombudsman's 2017-18 annual report.

Mr Wilkie had written to the ombudsman detailing continued issues with the agency's online compliance program, which matches a person's annual income as reported to the Tax Office with fortnightly income previously reported to Centrelink.

He said people who responded to income reviews with the agency by providing their payslips were clocking up higher debts than those who provided their bank statements. The department said this was "misleading".

"If a customer is unable to provide payslips and instead provides bank statements, the net pay shown on the statement is converted to a gross amount for their earnings calculation."

Tasmanian man David Felix said it took a complaint to the Ombudsman's office before he made progress with reviewing his debt notice with Centrelink. Mr Felix said he has repeatedly requested information from Centrelink about what income he originally reported when he was receiving Youth Allowance between 2012 and 2013. He was waiting for that information when he received a phone call from debt collectors on behalf of the agency.

"Nowhere in that period did they tell me that I owed them money," Mr Felix said. His case is still being reviewed by the agency, after it removed the debt from the collectors.

“The fact that the Ombudsman has now seen fit to investigate the matter again is proof that the robo-debt program is deeply flawed and must be shut down and replaced with one that is timely, accurate and fair," Mr Wilkie said.

“I thank the Ombudsman for seeing the significant public interest in this matter and I will continue to provide his office with evidence of problems with the system as I receive it,” he said.