Just two weeks after releasing iOS 6.1, Apple (AAPL) on Monday issued a new software update to address some serious bugs. The iOS 6.1.1 update was clearly rushed out — it is only available for the iPhone 4S at the moment — and it is mainly a response to Vodafone’s public warnings dissuading iPhone 4S users on its network from updating their handsets. A number of iPhone users have reported that their battery life has taken a hit since updating to iOS 6.1, but issues on Vodafone’s network were more severe — the carrier warned that iPhone 4S users might not be able to make or receive calls or SMS if they updated. iOS 6.1.1 is available immediately for iPhone 4S users as an over-the-air (OTA) update.