Apple have made the following announcement today and have launched a replacement program for those affected.
Apple has determined that a very small percentage of iPhone 5 devices may suddenly experience shorter battery life or need to be charged more frequently. The affected iPhone 5 devices were sold between September 2012 and January 2013 and fall within a limited serial number range.
Apple may restrict or limit repair to the original country of purchase.
If you believe your iPhone 5 was affected by this issue, and you paid to replace your battery, you can contact Apple about a refund.
This worldwide Apple program doesn’t extend the standard warranty coverage of the iPhone 5. The program covers affected iPhone 5 batteries for two years after the first retail sale of the unit or until March 1, 2015, whichever provides longer coverage.
Click HERE to see if you are legible.