The information on offer was not as comprehensive as that of Spark and 2degrees, Consumer said.
"However, Vodafone's annual summary was the best of all three providers, giving a useful overview of usage and spend and a prompt to consider switching, along with details of its other plans.
"This review shows that consumers are getting better usage and spend information from their mobile providers than they were before, but there are clearly significant opportunities for further improvement across the board – including for the top-ranked provider – which we'd like to see addressed before we run this study again," Telecommunications Commissioner Tristan Gilbertson said.
Consumer CEO Jon Duffy said, "Our research has found that more than half of all mobile consumers have been with the same provider for more than five years.
"Telcos are now sending you better information about what you've spent and what you've used. We'd encourage people to make sure they use this information. Being on the wrong plan or staying with an uncompetitive deal can cost hundreds each year."
Vodafone responds
"Vodafone has implemented annual summaries which provide an overview of customers' usage and spend over the past year and prompt customers to consider moving to a different plan that may be better suited for their needs," corporate affairs head Rich Llewellyn told the Herald.
"We started the rollout of annual summaries in December 2021, both via email and post. It is important to note that there are many different reasons why a customer may choose to be on a particular plan, such as device discounts, companion plans and added services.
Not all customers went through digital channels. Some discussed their plan via a call or in retail stores, Llewellyn said.
"This is particularly the case for a cohort of customers who may be vulnerable and most exposed to cost challenges.
"Therefore, weight must also be given to alternative means by which those customers are informed about the choice of plans that best meet their needs based on historic usage, and how those customers are encouraged toward the right plan."
2degrees responds
"Making things straight forward for our customers has always been a priority at 2degrees so we are chuffed Consumer NZ has seen this," said 2degrees chief marketing and strategy officer Zac Summers.
The watchdog did ding 2degrees for the lack of historical spending data on its annual summary.
"We plan to roll out a steady stream of new features, including how we display annual information," Summers said.
Spark responds
"We believe we've made great progress in this space including providing our customers hourly, daily, monthly data usage information and daily, monthly and yearly breakdowns of voice and text services for a 12-month period. We are also providing monthly and yearly spend information," a Spark spokesperson said.
"We've been working with the Commerce Commission to make improvements to the accessibility of our usage and spend information, with the aim of helping our customers to make more informed decisions when it comes to managing their mobile services,"