Battery broken again after a year?

Hello together! In December 2012 I received a new battery for our C (EZ 2008, 2,0d) around 160,-. So the battery is now quite exactly one year old. On Monday entered, did not start. Towing service called, with starter cables started without any problems. Today again the same game, too little juice to start, with start help easily jumped on. To the workshop ́s about 15 km, there was measured that the battery is 100% charged – this can be after so e in a short distance? It was further said that a mistake would be known from other C70, where the top control unit pulled power. For this there is even a software updaze, which was played (57,- Euro). I was curious. Did anyone else of you have an idea, or something like that already experienced? MfG charles164