Vodafone NZ spokeswoman Libby Middlebrook said the company was "disappointed and genuinely surprised" by the results as its own surveys found 65 per cent of broadband and landline customers were satisfied with its services, while 71 per cent of mobile customers were satisfied.
The company had invested heavily in customer care initiatives, including the hiring of 200 more customer support staff in the past year.
Meanwhile, Spark was rated 35 per cent for its internet services, the second lowest of any provider, and 41 per cent for its mobile services, the lowest rating for a mobile provider.
Spark spokeswoman Lucy Fallbright said the company was constantly working on improving its services.
"We acknowledge things like wait times when contacting our call centres can be improved," she said. "We employed 100 extra call centre staff last year and are training another 40 for our Christchurch call centre.
"We're also focussed on improving customer service by other means. Our 24 hour [online] live chat feature is increasingly popular and we've added a map to our site so customers can see if there's a problem in their area without having to call us."
The highest rated internet provider was small Manawatu-based company Inspire Net, which received a rating of 98 per cent. The highest rated mobile provider was Spark offshoot Skinny Mobile, with a rating of 84 per cent.
Most respondents had been with their providers for at least two years, with about 60 per cent committing to the same providers for five years or more.
Few respondents intended to change their internet service provider but 37 per cent said they were very likely to move to an ultra-fast broadband plan. Many of those who had already made the switch reported installation taking longer than expected.
Meanwhile, just over a quarter of respondents were subscribed to a video streaming service. Netflix was the highest rated streaming service, with a rating of 54 per cent.
Internet service providers
Top
•Inspire Net: 98 per cent
•Now NZ: 88 per cent
Bottom
•Spark: 35 per cent
•Vodafone: 30 per cent
Mobile service providers
Top
•Skinny: 84 per cent
•2degrees: 69 per cent
Bottom
•Vodafone: 42 per cent
•Spark: 41 per cent
Video streaming providers
Top
•Netflix: 54 per cent
•Lightbox: 25 per cent
Bottom
•Neon: 18 per cent
•Quickflix: 17 per cent
Source: Consumer NZ survey