Mercury is asking why their customers can't have their refund paid out to them.

The energy company wants Vector to quickly refund nearly $14 million to Auckland consumers.

Vector has admitted it overcharged its customers in 2013 after changing the way it set its prices.

Mercury says the refund should be paid directly to customers rather than Vector paying it back through reduced lines charges over two years.

Mercury’s chief marketing officer Julia Jack says some of their customers would appreciate that money in their pockets.

Jack said Mercury's offering to help Vector administer the refunds.

"We will put that rebate straight to the customers, carry the administration cost of that - make sure our customers get the refund."

Mercury has offered to top up their customers' refund by 5 percent if Vector hands over the cheque in the next 30 days