Apple is continuing to look into iPhone 4S battery issues which should have been fixed with the iOS 5.0.1 update.
The tech giant issued a variety of fixes in its iOS 5 update last week and was reportedly planning to correct a problem in the OS that had caused iPhone 4S battery life to rapidly diminish.
A number of iPhone 3GS and iPhone 4 users had also complained about poor battery life before Apple identified an issue in iOS 5.
Customers who downloaded iOS 5.0.1 flocked to support forums to vent their frustration.
"Lost 15 per cent in 45 mins and I didn't even use the phone. What happened? This update is no help," said one user.
"After updating my iPhone 4 to iOS 5.0.1 I've lost 50 per cent of battery in three hours. I've only listened to a podcast for 15min and the rest of the time the phone was locked still," another complained.
Apple told All Things D it was to continue investigating the battery issues.
"The recent iOS software update addressed many of the battery issues that some customers experienced on their iOS 5 devices," the company said.
"We continue to investigate a few remaining issues."
More frustration
iPhone owners aren't the only ones frustrated by Apple. Security researchers from CoreLabs claimed Apple had ignored warnings about flaws in a Mac sandboxing system.
Researchers said the flaw effectively meant rogue applications could circumvent the sandboxing system, which Apple is making compulsory for all apps on the Mac App Store from next March.
"A compromised application hypothetically restricted by the use of the no-network profile may have access to network resources through the use of Apple events to invoke the execution of other applications not directly restricted by the sandbox," Alex Horan, senior product manager for CoreLabs, said in a blog post.
"Despite our best efforts the vendor chose not to patch the code we identified as vulnerable."
At the time of publication, Apple had not responded to a request for comment.
It comes a week after Apple chucked security researcher Charlie Miller off its iOS developer programme after he uncovered a flaw that allowed rogue apps to bypass the code signing restrictions and secretly install malware onto Apple devices.
Apple subsequently patched the vulnerability in the same iOS 5 release it was due to fix battery issues.
