Consumer complaints about both Telstra and Optus have shot up during the quarter to March 2017, according to the latest complaints ratios published by the Australian Telecommunications Industry Ombudsman (TIO).
Every quarter, the TIO, in conjunction with Communications Alliance, publishes a Complaints in Context report covering landline, mobile, and internet service complaints from residential and small business consumers.
Unlike last year, when Vodafone's complaints rose higher than Telstra's, Telstra saw a figure of 9.3 complaints per 10,000 services in operation (SIO), up from 6.8 complaints last quarter.
Optus' complaints also hit 9.3 per 10,000 SIO, up from the 6.7 reported at the end of December.
Pivotel's also rose, from 1 to 1.3 during the quarter, while overall complaints about telecommunications rose from 6.4 to 8.4 complaints per 10,000 SIO.
But while Amaysim and Vodafone are losing mobile market share as Optus and Telstra gain more customers, they are improving on the complaints front: Vodafone's complaints fell from 5 to 3.9 per 10,000 SIO quarter on quarter, and Amaysim's from 1 to 0.9.
Vodafone applauded its own performance, pointing out that its complaints ratio was more than 50 percent lower than the industry average, and far lower than Telstra and Optus.
"We're always striving to provide the best possible experience for our customers every time they interact with us, whether it's using our network, chatting to us online or on the phone, visiting one of our stores, or using our MyVodafone app," a Vodafone spokesperson said.
"A 22 percent decline in the rate of complaints between the December and March quarters suggests to us that we've continued to improve the service we offer, and we're very pleased we've been able to do even better for our customers."
For its own part, Telstra attributed its rise in complaints to the process of moving a significant number of customers from traditional fixed-line broadband onto National Broadband Network (NBN) services.
"We recognise this transition can involve disruption for some of our customers," a Telstra spokesperson told ZDNet.
"The data shows that a significant volume of TIO complaints are for customer experiences relating to NBN. There are challenges here for the broader industry.
"We are working with NBN where we believe changes can help improve the NBN experience. We're also working on a number of initiatives to reduce complaints overall as part of improving the customer experience."
By comparison, complaints about Vodafone -- which is not launching NBN services until later this year -- are unaffected by the NBN rollout.
The TIO's annual report on total consumer complaints last week similarly showed a 33.5 percent year-on-year increase to a total of 65,970 complaints to the TIO about all telco services during July to December 2016.
Of these, 24,641 complaints were in relation to internet services, representing growth of 53.6 percent year on year; 23,331 were about mobile phone services, a rise of 18.8 percent; and 17,998 were on landline phone services, rising 32 percent.
Customer service made up 47.9 percent of all complaints, followed by billing and payments issues, at 39.4 percent; faults, at 35.7 percent; complaint handling, at 28.9 percent; contracts, at 20.2 percent; connections, at 15.6 percent; and credit management, at 10.5 percent.
New South Wales made the most complaints, at 21,040, followed by Victoria, at 18,354 complaints; Queensland, at 11,784 complaints; Western Australia, at 5,408 complaints; South Australia, at 5,340 complaints; Tasmania, at 1,213 complaints; the Australian Capital Territory, at 1,067 complaints; and the Northern Territory, at 420 complaints -- with Victoria and South Australia making the most complaints proportionally.
In terms of current mobile market share in Australia, market research company Kantar published its latest statistics earlier on Thursday, revealing that despite competition, Telstra has yet again increased its mobile market share to a total of 41.4 percent.
As of March 31, Telstra's post-paid market share grew by 2 percentage points for a total of 42.8 percent, although prepaid fell by 2.8 percentage points down to 38.9 percent of the market.
Optus also gained market share, albeit very slightly, from 22.7 percent to 22.8 percent total mobile market share as both prepaid and post-paid each rose by 0.5 percentage points.
Vodafone Hutchison Australia fell from 15.3 percent total mobile market share this time last year to 13.9 percent as of March 31 this year. It lost market share across both post-paid and prepaid, from 15.8 percent down to 13.7 percent and 14.3 percent to 14.2 percent, respectively.
Amaysim stayed fairly stagnant, losing just 0.1 percentage point of the total mobile market for a share of 4.7 percent as prepaid customers left but post-paid customers remained.
Updated at 6.30pm AEST, May 17: Added comment from Telstra spokesperson