When approaching the mountain there should be no delay in turning downwind as soon as you experience the forced decsent. You certainly should NOT consider tolerating the uncontrolled descent in the hope that it might get better. Your options are diminishing with every passing second.
Selecting a higher MSA may have allowed you to continue, it may not. Your headwind component could have been even stronger higher up and rotors can extend quite some distance from the mountain anyway.
A decision to turn back and land safely is always the correct one, so well done for that.
I can recommend an instructor in Switzerland who will teach you everything you need to know about mountain flying and it will be the best thing you could possibly do in an aeroplane that doesn't have hosties!