Spark spokeswoman Lucy Fullarton said the company has 2.1 million mobile connections and 680,000 broadband connections.
"While we will always work to reduce the number of customer complaints, it is worth noting that a large proportion of the complaints to the Commission related to the $1.50 fee for a paper bill and our price increase late last year - changes which Commission believed not likely to be a breach of the Fair Trading Act."
She said Spark paid close attention to concerns raised by customers and the Commission and moved quickly to improve processes or upskill staff as appropriate.
The complaints were considered by the commission to not be a breach of the act.
A quarter of New Zealanders' complaints under the Fair Trading Act relate to just 24 traders, the report found.
It also found that online trading generates 55 per cent of Fair Trading Act complaints - double the number laid against physical retailers.
The data comes from a range of sources including the commission, Government and community agencies.
The commission also found that telecommunication providers and home appliance retailers continue to generate the most complaints overall.
Meanwhile, motor vehicle credit contracts generate 30 per cent of credit complaints, and finance companies are the most complained about lenders - followed by mobile traders.
Auckland Academy of Learning was investigated by the Commission last year as a result of complaints about software sold door-to-door by the company, Consumer New Zealand reported.
The 'Computer Aided Mathematics Instruction' (CAMI) software was sold for from between $2750 and $11,000 and payments could be made over four years.
And 96 of the 99 complaints received by ANZ were related to the Commission's interest rate swap investigation.
The Commerce Commission enforces three key laws:
• The Fair Trading Act (1986) prohibits false and misleading behaviours by businesses.
•The Credit Contracts and Consumer Finance Act (2003) protects consumers when they borrow money
•The Commerce Act (1986) prohibits anti-competitive behaviour and mergers
The report also identified 93 issues and risks to consumers and markets.
The issues included:
• Lenders charging unreasonable fees
•The mobile trader business model
•Disproportionate number of complaints generated by a small number of traders (in particular the telecommunications and domestic appliance retail industries)
•Issues that affect vulnerable consumers
•Participation in industry associations enabling anticompetitive conduct
•Misrepresentation of country of origin labelling
•Supermarket misrepresentations
Minister of Commerce and Consumer Affairs Paul Goldsmith welcomed the report.
"I am pleased to see this comprehensive analysis from the Commerce Commission which helps to inform and prioritise their work."
24 most complained about companies:
• Spark NZ Trading Limited - 128
• Vodafone NZ Limited - 112
• Auckland Academy of Learning Limited - 106
• ANZ National Bank Limited T/A The National Bank and ANZ - 99
• Sellers on Trade Me - 78
• New Zealand Business Funding Centre - 50
• Progressive Enterprises Ltd (Countdown) - 45
• Air New Zealand Limited - 43
• GrabOne Limited - 39
• Noel Leeming Group Limited (Noel Leeming) - 35
• Brand Developers Limited (TV Shop) - 35
• Foodstuffs (NZ) Ltd (New World/PAK'nSAVE/Four Square) - 34
• ASB Bank Limited - 33
• Parking Enforcement Services - 31
• DSE (NZ) Limited (Dick Smith Electronics) - 30
• DB Breweries Limited - 29
• Callplus Services Limited (Slingshot Communications) - 27
• Dead Sea Skincare - 27
• The Warehouse Group Limited (The Warehouse) - 26
• NZ Sale Limited - 26
• KLiB Technologies Group Limited (24/7 Hosting and Web Design) - 25
• Two Degrees Mobile Limited (2degrees) - 24
• PB Technologies Limited - 24
• IPL Laser Solutions Limited - 23
