BEIJING, Dec. 29 (Xinhua) -- Apple will replace a number of their old-version iPhone batteries at a lower price next year, following a public outcry over iPhone slowdowns.

Apple users have been complaining that a software update of iPhone 6 and following models caused their phones to slow down, and many believe it was deliberately done by the company to drive new sales.

In a message to customers posted Friday morning, Apple denied such accusations, saying they "have never -- and would never" intentionally shorten the life of its products, or degrade user experience to drive customer upgrades.

The company said the slow down in performance was to avoid unexpected shutdowns of old iPhones as batteries age.

But the company apologized for the "misunderstanding." "We know that some of you feel Apple has let you down. We apologize," it said.

Apple is accordingly reducing the price of out-of-warranty iPhone battery replacements from 79 U.S. dollars to 29 from late January 2018 to December. On the Chinese mainland, the price will be reduced to 218 yuan from 608 yuan during the same period. The service applies to anyone with an iPhone 6 or later model whose battery needs to be replaced.

The company also said it would issue an iOS software update with new features that make the battery condition more visible to users.