Samsung and Apple have both been forced to issue warnings to customers over problems with its smartphones.
Apple has announced a replacement programme for iPhone 5 phones which have broken sleep/wake buttons.
The tech giant said the buttons on some phones made before May 2013 were prone to breaking or not working, and said that users would be able to check if their device was affected and replace the button free of charge.
Apple has launched a webpage in which users can input their serial number and book a return, or arrange to drop it off in person.
In a separate incident, Samsung said some users of its new Galaxy S5 smartphone were having problems with the phone's camera.
In a "very limited proportion" of cases, Samsung said, the camera either did not work or failed soon after using, due to "complications in the Read Only Memory component which stores the information necessary to operate the camera".
Samsung said that affected customers can get the phone replaced by contacting customer support.