Telecom has angered internet customers by hiking the price of unlimited broadband access.

From next month, customers with no monthly data limit will have to pay an extra $10 to keep downloading as much as they want.

Sticking with the old monthly fee of $49.95 would mean dropping to a 10GB cap. Customer Peter Collis was sent a letter saying his existing Go Large plan was ending, and advising he switch to the new Big Time scheme.

He said he wasn't happy about the extra $10, but felt Telecom had him "over a barrel."

"To change providers would be a nightmare," he said. "It is surprising that they still have such a monopoly that they can put the price up."

He was unconvinced by promises the new service would be faster. "I'd say there would be a lot of people on Go Large that would be quite angry."

Telecom home PR manager Emma-Kate Greer said the old plan hadn't been sold since February 2007, and an improved product had been in the works since then.

She said Big Time offered a better service: the speed of the network would be managed more effectively at peak times, and download and upload speeds would be faster.

Existing Go Large customers could try it for three months at the old price. Greer refused to say how many people were affected by the change.

None of Telecom's major competitors offers an unlimited data service. Orcon has a 25GB plan for $119.95, including a home phone line and unlimited calls around New Zealand.

Vodafone's highest-use plan costs $120 a month for 40GB, also including a home phone.

External communications manager Paul Brislen acknowledged Vodafone prices would be "refreshed" soon, "but as far as I know there are no plans to put them up by $10."