Labour has promised to prevent phone, internet and insurance companies charging loyal customers more than new ones, if it is elected on November 7.

The party would also ban "fake discounts" and stop big price hikes once introductory offers end.

Leader Chris Hipkins said on Monday people should not have to spend hours comparing prices, reading the fine print or changing companies to get a fair deal.

"Too often, people who stay with the same phone, internet or insurance company for years end up paying more than a new customer.

"Many find their bills go up when a deal ends, or that a sale wasn't the bargain it looked like."

Under Labour's policy, phone, internet and insurance companies would not be able to charge longstanding customers higher prices than new customers.

Its policy document says power companies are already required to check their customers are on the best plan.

It would also prevent companies shifting customers on to "unjustifiably" expensive plans when an introductory deal ends.

Labour also plans to ban "fake discounts" and misleading specials, saying advertised discounts must be based on the lowest price charged for that product in the previous 30 days, saying customers should be able to trust they are getting a genuine saving.

Commerce and consumer affairs spokesperson Arena Williams said New Zealanders deserve fair prices, honest deals, and more money left over at the end of the week.

"Labour has a plan to tackle the cost of living and make sure Kiwis get a fair go on their household bills.”