It was nothing more than any holidaymaker might do.

Wellingtonian Magnus O'Neill pulled out his iPhone while holidaying in the Cook Islands, checked Facebook and used Wikipedia to research his hotel and what tropical fish he might see.

The online checks would have cost him about $4 in New Zealand. Instead he now faces a bill from Telecom for $2000.

His roaming consumed a modest 70 megabytes of mobile data. But what Mr O'Neill didn't realise was that he was being charged $30 a megabyte, a price he believes was "extortionate and unfair".

He admits he didn't check Telecom's data roaming charges but believed the company failed in its "duty of care".

"There are reasonable assumptions which a customer may make in travelling overseas, specifically as to the reasonable amount of charges which may be incurred, and Telecom has a duty of care to inform and correct such reasonable assumptions."

As Cook Islands Telecom is majority owned by Telecom, he believes the roaming charges were well within its own control.

He has lodged a complaint with the Telecommunications Disputes Resolution Service and said he was advised by it to also contact the Commerce Commission.

Telecommunications Users Association chief executive Paul Brislen said he was sympathetic and the pricing was "stupid and ridiculous".

In Europe, regulators were forcing the wholesale price of data roaming down to 5c a megabyte, he said.

Telecom spokeswoman Stephanie Fergusson said Telecom had offered to write off $977.87 of Mr O'Neill's bill, which he had run up before he received a delayed "courtesy" text from Telecom advising him that New Zealand data rates would not apply during his visit to the Cook Islands.

"There is a bilateral agreement between Telecom New Zealand and Cook Islands Telecom, which operates completely independently, and we negotiate the roaming agreement like any other carrier," she said. Mr O'Neill offered to pay $5 a megabyte after the text message was received.

This month Telecom will introduce a new service that will let customers set their own dollar limits for data roaming that will stop them from racking up bigger bills unless overridden. It will also text customers when they consume more than 2Mb, 60Mb and 100Mb when roaming overseas.

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