Spark has been issued a warning from the Commerce Commission and ordered to pay more than 15-million dollars in refunds to customers

The commission says Spark charged more than 112-thousand wireless and fibre customers for wire maintenance services they didn't need between 2014 and 2021.

Chairwoman Anna Rawlings says Spark's conduct created an impression that a wire maintenance service was suitable for everyone.

Spark has since stopped selling the service to those customers, has paid back most of what it owed, and is urging customers to check if they are eligible for a refund.

The company says it apologises to anyone affected and its committed to making sure what happened doesn't happen again.