Optus complaints have been driven by mobile-related services, according to the TIO, such as faults, inadequate spend controls and disputed internet charges.

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Complaints about Vodafone also increased 11 per cent, with complaints primarily about inadequate spend controls on mobile phones and internet usage charges on mobiles.

Meanwhile, complaints about Virgin also increased by 33.1 per cent and complaints about TPG dropped 23.7 per cent.

Overall, consumer complaints about telcos dropped 2 per cent in the 2011-12 year to 193,702.