Pay-TV operator Sky Network Television has paid back more than 2500 customers who were overcharged when they tried to upgrade their subscriptions.
Customers who tried to sign up for an offer to get a premium channel for $1 a month earlier this year were instead charged the normal price of $25, the Commerce Commission said.
The commission warned Sky that it was possibly in breach of the Fair Trading Act for misleading customers.
A customer complained to the commission after problems with Sky's voice recognition phone service line meant he was overcharged.
An investigation by the commission found 2633 other subscribers were in the same boat.
Its competition manager Greg Allan says it only issued a warning because Sky co-operated with its investigation and acted quickly to put the matter right.
Those affected had their accounts credited, costing Sky $55,990.
It also made sure the Starship Foundation charity, which was supposed receive a $1 donation from each upgrade, got the money it was entitled to.
NZN