'What if I already upgraded my storage plan prior to this extension?
If you upgraded your storage plan before September 30, 2012, we have automatically extended your upgrade at no additional charge until September 30, 2013.'
Have they charged you? If so this should cover you until 2014; if not they won't until 2013. If in doubt you first check in your account details and if necessary contact Support.
Well, they sure charged me! They sent the threatening emails about losing data if I didn't pay. And yes I had 25 GB.
You were originally a MobileMe member? It's possible that you paid before the extension to next year: I would imagine that the result will be that in effect you've paid for the year from September 30 2013. Check your account details and see whether this is confirmed.
If you have been charged incorrectly you will have to take it up with Support: