And the welfare agency's bosses are defiant in the face of the savaging of their customer service efforts by the Auditor-General, with the Department of Human Services telling Senate Estimates that it may not heed the recommendations of the Auditor's report.

Departmental Secretary Kathryn Campbell hit back at some of the criticism in the Auditor-General's report, saying it was not clear why so there were so many "abandoned" calls and it was possible that people hung up after they got the information they needed from recorded messages.

"We did raise with the ANAO [Australian National Audit Office] that these were very complicated and intricate services to provide," Ms Campbell said.

"The point we tried to make with the ANAO on a number of occasions around what are called abandoned phone calls.

"Sometimes it can be that customers have received the information they are looking from pre-recorded."

The Auditor's reported that the "average" wait time that Centrelink reported to the government of nearly 17 minutes did not reflect the true experience of many customers, with 30 per cent on hold for 30 minutes or more.

The audit team questioned why the giant department could not follow the lead of other government agencies, like the Tax Office, and give callers a more realistic idea of how long they might be waiting.

But Ms Campbell told the committee that Department of Human Services could not be compared to other call centre operators like Telstra, Qantas or the Australian Taxation Office because of the tens of millions of calls coming through to Centrelink each year.

The secretary said she and her colleagues took the recommendations of the Auditor-General seriously but would not commit to following all of the report's recommendations until they had determined whether each of them was appropriate.