Apple has come under pressure from a Chinese consumer group demanding answers over the slowing iPhone debacle.
The Shanghai Consumer Council wants an explanation from Apple about the slowing of older iPhones following software updates.
In a letter to Apple this week, the council requests an explanation for the slow-down and information about what Apple plans to do to remedy the issue.
The non-government organisation claims to have received 2,615 complaints about Apple products and services in 2017 versus 964 complaints in 2015.
Earlier this month, Apple was also asked by the US Senate committee to answer questions about the iPhone problem.
Apple issued an apology on December 28, cut battery replacement costs and pledged to change its software to show users whether their phone battery is good.
Lawsuits have been filed against Apple over the issue in California, New York and Illinois, alleging the company defrauded users by slowing down devices without warning.
There has also been a legal complaint in France, where so-called “planned obsolesce” is against the law.
Nevertheless, Apple shares have recovered from a low of $169 at the end of December to trade at $177.
Over recent weeks, investors have been more focused on the impact of US tax-cutting measures, which should see Apple repatriate billions of dollars to the US, potentially boosting the cash it returns to shareholders as well as making it more likely to the company will pursue big acquisitions.
Apple shares have gained around 47% over the past year.