COMPLAINTS received about Centrelink increased by 38% over the previous year, according to the Commonwealth Ombudsman Annual Report from 2015-16.
They increased from more than 6000 in 2014-15 to nearly 9000 this past financial year.
A recently released report highlighted that phone and online services as well as complaint and review process and records management continue to be key points of frustration.
This follows a report submitted by the Ombudsman in 2014 regarding the same issues but this year's report stated that "these have remained recurrent themes in 2015-16".
"The inability to access Centrelink in order to fix problems with online services or generally to make a complaint resulted in added frustration," it read.
In its own 2015-16 annual review, the Department of Human Services revealed that complaints nearly doubled from last year, or an increase of 86%.
But Centrelink claims the higher amount of complaints is due to the introduction of an online feedback form.
It further stated that "the department takes a collaborative approach" in response to customer complaints.
"In 2015-16 complaints handling training for our large service delivery workforce was completed," it read.
"The training included first contact resolution and new escalation procedures for complex and sensitive complaints."
The Ombudsman's report can be accessed via http://www.ombudsman.gov.au/__data/assets/pdf_file/0022/41584/ombudsman-annual-report15-16.pdf while the Department of Human Services' report can be accessed at https://www.humanservices.gov.au/sites/default/files/8802-1610-annualreport2015-16.pdf.