National Broadband Network customers are five times more likely to complain about their service than a non-NBN user, as frustrations continue to surround the nation's biggest infrastructure project.

More than 13,406 complaints were made to the Telecommunications Industry Ombudsman about NBN services in the last financial year, which accounted for 11.9 per cent of all complaints received by the TIO, an increase from 5.4 per cent the year before.

Complaints made to the Telecommunications Industry Ombudsman about NBN services increased by 5.4 per cent compared to the previous financial year. Credit:Adam Turner

Consumer advocacy groups believe a lot of the disappointment around the NBN could be mitigated with more transparency.

Teresa Corbin, CEO of the Australian Communications Consumer Action Network (ACCAN) said clearer information was needed to differentiate between theoretical speeds and what could actually be achieved.