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Homes with piped or bottled gas are facing increasing prices and fewer choices, while complaints about services doubled in the last year.
In New Zealand, 600,000 households use gas, and commercial customers were also impacted.
The manager of Consumer NZ's Powerswitch service Paul Fuge was expecting to see price increases of around 10 percent on average, but he said that will vary.
"The price changes people are seeing will vary considerably depending on [someone's] location and which retailer they're with."
Fuge told Nine to Noon, so far Mercury was the only gas supplier to announce an increase - at 9.7 percent - but Powerswitch has already seen examples of increases up to 20 percent.
Consumers were also being hit in the pocket by daily fixed charges on gas, on top of their electricity charge, he said.
"That's what really makes gas uneconomic for households because you end up paying two daily charges rather than one.
"So you have to have an electricity connection, you can't avoid electricity but you can avoid gas. Unfortunately if you've got a gas connection you end up paying a daily charge, on average about $2 a day, so that really adds up.
"We've had examples of people coming to Powerswitch and asking us why their powerbill is so high and what we've discovered is where they've got a gas connection and they've only got say a gas hob, they end up paying a very high price because their daily charge is way in excess of the gas they're actually using."
Fuge said while the daily charge was small it could add up to between $800 to $1000 a year.
"There's two things happening... the network is getting more expensive.
"That's because it's an ageing infrastructure and you've got other things like the high cost of replacing infrastructure and the high cost of capital, it's affecting the network charges.
"On top of that you've got scarcity and then, of course, scarcity will increase price. So as the gas reserves get lower and there's more competition for gas," he said.
Gas New Zealand, which represented the gas industry, was aware of high prices and difficult market conditions but chief executive, Jeffrey Clarke said there was a strong future for gas as a fuel.
"So I think the whole gas sector and electricity sector are working to put more supply in and that's the reality.
"We are short on supply. So prices are going up and there's a lot of investment that's needed in the network."
Clarke said in order to increase the supply he'd like to see more investment in renewable gas which is made from agricultural waste, food waste, wastewater, which releases gas when it decomposes.
"The reality is that we need gas at the moment to support our electricity system, so we can't do without it.
"So if you look at the Climate Change Commission's modeling, they assume that we will continue to use gas to support our renewable electricity generation right out to 2050 because we need something to balance off the variability of renewables, so we have to have it."
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