Telecommunications retail service providers were the most complained about industry in the year to 30 June 2018, the Commerce Commission says in its Consumer Issues Report 2017/18.

Of the 7,452 complaints lodged during the year, 584 (7.8%) were about telecommunications retail service providers. This was follows by Motor vehicle retain and sales (420 complaints), domestic appliance retail(391), online ticket reselling (359) and construction (287).

Most of the complaints (6,770) related to the Fair Trading Act 1986, with 318 lodged under the Credit Contracts and Consumer Finance Act 2003 and 364 under the Commerce Act 1986.

Considering key emerging themes in complaints, the Commission says purchasing online is both beneficial and risky for consumers. It says 24% of the Fair Trading Act complaints it received were about purchases considered or made online.

"Complaints show that some consumers have trusted the legitimacy of an online trader and then felt let down," it says.

A common theme in complaints involves consumers being unable to make contact with overseas-based traders to resolve concerns about product delivery or quality.

Consumers are also faced with increasingly sophisticated marketing techniques. The Commission says some traders, especially those selling online, have developed marketing techniques that some consumers say have caused them to make hurried, spontaneous purchases.

"Complaint narratives about in-store purchases suggest that consumers find the complexity of some technologies (such as smartphones) and/or contract offers (such as smartphone plans) makes it difficult for them to decide on the goods and services that best meet their needs."

The Commission says its intelligence continues to suggest that some lenders are failing to comply with the Responsible Lending Principles under the Credit Contracts and Consumer Finance Act. It says some lenders - including finance companies, mobile traders and lenders offering high-cost short-term loans - are not lending responsibly. Many complaints also related to whether the lender undertook reasonable inquiries about borrowers' circumstances and/or specific needs.

Complaints continue to be received about the various fees set by lenders for motor vehicle financing, and also that lenders are not sufficiently disclosing the terms and conditions  of borrowing before consumers sign loan documents.