As yet I don't believe any 2012 car has failed, so in answer to your question, YES, an updated tensioner should solve the problem, unless it just went, all parts can fail so if your unlucky a new one could go!!
Saying above however 2012 cars have only had 1-2 years use and so who is to say this fault IS fixed until a car gets passed the 3 x year mark with a nice number of miles this seemed to be the break point.
So watch this space for more stories, fingers crossed it's sorted though or my GTI will be getting sold when the 2x warranty runs out