Legacy manual down shift problems.
 

I have a 2011 legacy estate 2.0 diesel manual. 83,000 miles.

So when the car is cold I have trouble down shifting into 3rd 2nd and 1st (hard to go into gear and some times will not go into gear). After the car warms up it isn't as bad. Gearbox oil has been changed and still doing the same thing. Was told by the dealer I bought it from that it can't be fix even if a new gearbox was out in as it is normal for the make/model/miles and that it is a bad design gearbox.

Is this normal or can it be fixed?