Apple has opened up a new exchange program, for their customers affected with overheating of the company's 5W European USB Power Adapter. These are the adapters that shipped with Apple's previously announced iPhone 3GS, 4 and 4S smartphones from the dates between October 2009 to September 2012. The Programs is limited to a number of countries in the European region.
Customer safety is always Apple’s top priority, and we have voluntarily decided to exchange every affected power adapter for a new, redesigned adapter, free of charge. We encourage customers to exchange any affected adapter for a new one as soon as possible using the exchange process below.
You can identify your chargers, whether it is eligible for the exchange program by model number and the color of the letters "CE" outlined in red from the above picture. If you have an adapter with the model number, A1300 and the color of letters "CE" is in solid gray, you can take it to the nearest Apple Retail Store or to a participating Apple Authorized Service Provider in the country.
Note: Other Apple 5W USB power adapters are not part of this program.
Source: Apple