The agency and its parent department came under sustained criticism this year after an National Audit Office report found nearly a quarter of the 57 million phone calls made to Centrelink last year went unanswered and that Australians spent 143 years waiting in vain to speak to Centrelink in 2013-2014, before simply hanging up, the auditors calculated. WA Greens Senator Rachel Siewert. Under questioning from Greens Senator Rachel Siewert at a late-night hearing on Thursday, senior DHS official Grant Tidswell said the decision on how many calls to block was a trade-off between the demand for service and the department's ability to provide it. "It's always a trade-off…trying to manage the workload and demand and the challenge between demand and supply, but in previous years we've had far, far higher numbers, well over 30 million," the public servant told the committee. But it was the emerging "redial" app technology that was really adding to DHS's well-documented telephone woes, Mr Tidswell said.

"Some people have got an application that they can get on their smartphone and it'll just keep pinging and pinging and pinging, so some people use it," he said. Centrelink clients have vented their fury over the welfare agency's customer service performance. "Some people use it to get concert tickets and win prizes and we're getting people upwards of 800 to 1000 times at that time so we are battling new technology with people doing that at peak demand times. "So what we're seeing is more and more attempts as people try to get through." Mr Tidswell said his agency was keeping up its efforts to direct callers to use the website or apps instead of the telephones.

"The last financial year we had more digital transactions than the combined transaction of face to face and telephony, so we're improving in that area," he said. Senator Siewert said it made her "heart sink" to hear the soaring figures on blocked calls. "To hear that 13.7 million has now swelled to 22 million makes my heart sink," the West Australian Senator said. "From questions during estimates it appears that Centrelink has no interest in taking further action in driving down the worrying statistics. "At a time when the government is happy to paint people on income support as 'dole bludgers', having infrastructure in place that clearly can't cope with demand shows a fundamental flaw.