So I went back to the store because my sunglasses slided down my nose. He bended the end of the arms a bit. I think he used a hair dryer or something similar to soften the arms a bit.
That wasn't enough so I came back a few weeks later to ask for the same thing. Then he bended them a bit too far... and one of the arms a bit outward.

You can see it in the attached picture. The right arm sometimes doesn't even hook behind my ear!
Now I'm trying to bend them in a better shape again. Does anyone have any tips? I tried holding the arms in hot water, to soften the material a bit. (I considered holding them close to a candle, but it's probably too hot.)
Also, a friend bended the nose bridge a bit and I'm not too happy with that.

It's not symmetric anymore. Can I safely bend it back?