"I needed to access data, I needed to use my phone to make a call and sort out my banking issues," he said.
Johnston said he had his 2degrees sim in his phone for less than 10 minutes before he gave up, headed to a kiosk at the airport and purchased a local simcard.
Assuming roaming was a no-go on his New Zealand sim, he stored it in his wallet and used the local card for the remainder of his month-long solo trip.
"I went all over Argentina for two weeks, then went to Peru for two weeks," he said.
In total, Johnston said he spent around $40 NZD on data on this local sim over the month he was overseas.
"I was using a lot of the wifi that was available in the hotels and stuff.
"Those first two weeks I was floating around doing the tourist thing in Argentina,checking out the beaches and the city."
"The last two weeks of the holiday I couldn't use wifi as I was in the jungle."
He was therefore horrified when he arrived back in New Zealand to find he had been billed $607.38 by 2degrees.
While around $100 of the initial $600 bill accounted for Johnston's monthly plan and phone repayment bill, the other $508 was a charge for the 50.81MB of data 2degrees' said he had used.
On Tuesday afternoon after the Herald contacted 2degrees for comment, a spokesman for the company said Johnston did use the data but the fee would be waived as a "goodwill gesture".
The spokesman added that Johnston was sent several text messages to alert him to the cost of roaming in Argentina.
"The glitch was with our escalation process which should have seen the bill passed on to someone who could review it properly," the spokesman said.
But Johnston had already been cut off the service as he had not paid the bill.
Johnston said the times given to him by 2degrees for periods when he had apparently used their services, didn't add up.
He also said he found it difficult to believe the company would allow customers to rack up that much of a cost without letting them know they were doing so.
He called the company to get to the bottom of what he assumed was a botch-up, and was offered a 20 per cent discount by a customer service supervisor. However, he was told the fee would not be waived.
Not satisfied, Johnston also emailed 2degrees to complain.
A response said the company was looking into the charges to check they were "correct and valid".
It was almost a week after this second complaint from Johnston and an inquiry from the Herald when he heard back from another customer service representative.
Johnston had initially considered jumping ship to Vodafone, but after since being told the fee would be waived he had decided to stay with 2 Degrees.
After speaking to the customer service representative he was happy to hear the company was considering changes to its customer service system to better handle similar inquiries.
"Fingers crossed it's not just talk and they'll put it into action."
