Q: IOS9 Has Wrecked my iPhone 5

I have an iPhone 5, completely as bought, which I updated to IOS9 a few weeks ago and have been having grief ever since, problems include:

• Unresponsive / inaccurate touch screen
• Frequent failure to load past the loading screen
• Certain apps such as Instagram have become non-responsive and have to be deleted and reinstalled.
• Keyboard randomly slows to a snails pace.
• Phone often crashes in settings menu when going to select wifi.
• 3G hangs and needs to be turned to airplane mode to reset the connection.
• Battery indicator drops from 25% to 5% or such like.

My phone was absolutely fine before with IOS8 and there is plenty of storage available.

I have tried to restore the phone, but whenever I do I get a 'This device isn't eligible for the requested build' message. I've tried all the fixes but nothing works. Friends have been commenting on similar problems with iPhone 5 on the new OS.

Anyone have any ideas?

Thanks,

Tom