- There are no widespread issues with battery life for iPhone 4S on iOS 6.1
- As a tech, I know that one of the first troubleshooting steps is to update the device to the latest iOS.
- Yeah, he should have asked your permission before updating to 6.1, but remember you failed to ask him not to.
- Apple does not provide a way to downgrade iOS versions.
Your best option is to put some pressure on your IT department to update their support for 6.1. They should keep up to date, not force others to stay below the avaible iOS version.
I have a 4S and i was on 5.1.1 up until 48 hours ago and the battery life is definitely better than when i was running 5.1.1. I charge my phone every two days now instead of daily!
My 4S is a year old now, WiFi also works just fine. As others have said there is no way to downgrade sadly so your stuck with 6.1, even if they replaced your phone your going to get 6.x on that too.
Try doing a full restore and setting it up as new, i know this is not ideal but it's the best way to try and resolve your issues. I would also go back and have a few words with the idiot who upgraded your firmware without your consent! He should have informed you that you were running an older version and that a software update was available and that it may resolve your issues and request permission to proceed to update the device.