Can I update from Trados Studio 2014 to 2015 and how much would it cost me in Euros please?

I already have Trados Studio 2011 and 2014.  How much would it cost to update to 2015 and what are the benefits of 2015, because I found it difficult to use

2014 and preferred to use 2011 until recently.  Does it have a simple outlay, easy to save docs, etc? 

Thanks

Eileen