Vodafone NZ is increasing the daily cost of its roaming plan from $5 a day to $7 a day from July 11 - a 40 per cent increase.
The telco says that at the same time, it is increasing the number of countries covered by the deal from 70 to more than 100.
The move follows a $3 price rise across all of Vodafone's broadband plans in the New Year, which it said was the result of accumulated price rises by wholesaler Chorus.
Some customers will also be able to get a refund if they don't like the roaming increase.
A statement on Vodafone NZ's website says, "If you are on a mobile plan governed by the Consumer Terms, and believe that Daily Roaming for $7 a day has a detrimental impact on you, you are entitled to cancel your contract without incurring an early termination charge. If you are paying off a device on an Interest-free Payment, that device will still need to be repaid as per your Interest-free terms.