iiNet, Telstra and TPG saw the biggest year-on-year falls in new customer complaints filed against them, according to statistics released by the Telecommunications Industry Ombudsman.
Unveiling its annual report today, the TIO noted that new complaints lodged against iiNet fell 26.4 percent in 2011-12, compared to the prior financial year.
In real terms, that meant the 2974 new complaints against iiNet that the TIO received in 2010-11 fell to 2188 new complaints in 2011-12.
Telstra also saw a major downward shift in new complaint numbers, falling from 78,949 received in 2010-11 to 61,991 in 2011-12 - a 21.5 percent year-on-year reduction.
TPG also saw a substantial drop in the number of new complaints about it lodged with the TIO. Its numbers fell from 4212 in 2010-11 to 3443 in 2011-12, equating to an 18.3 percent fall.
iiNet has been heavily focused on customer service over the period, particularly around garnering improvements in net promoter scores (NPS), a benchmark for customer satisfaction.
Telstra has also made customer service improvement a key focus under CEO David Thodey's reign.
More modest year-on-year complaint falls were experienced by Dodo, Crazy John's and the former Hutchison brand '3', though the latter's falls could be the result of the gradual wind-down of the brand during the financial year.
Mobile telcos generally did not fare well in new complaint numbers, with most experiencing a rise in reported complaints, some substantial.
New complaints about Optus rose 46.9 percent year-on-year to 41,602. Virgin Mobile saw a rise of 33.1 percent over the same period, equivalent to 8177 new complaints, while Vodafone clocked an 11.3 percent increase in new complaints.
The TIO attributed Optus' showing to "mobile service-related issues such as faults, inadequate spend controls and disputed internet charges".
The mix of figures meant that overall complaints in the telco sector actually fell in 2011-12. However, the TIO noted that complaints about mobile phones were up 9 percent overall.
"There has been a clear trend, since April 2012, of reduced complaints, with the last quarter of 2011-12 being our quietest for almost two years," ombudsman Simon Cohen said.
"This is a positive sign that reflects the focus by a number of telcos on improving their customer service."
There was a 150 percent increase in complaints about disputed internet usage charges in 2011-12, compared to the prior year, equating to 10,556 "issues".
Eighty-three percent of the internet usage cost complaints came from mobile phone users.