Yesterday I tried to separate the headband top/bottom parts using a prying tool - no luck.
Didn't apply to much force though - afraid not to break something.
I tried starting from the middle and from the side as well. Maybe I will try some other time when I feel more courageous
I pushed the leather back in place one last time and I am using this neoprene cover for now.
It looks ugly I know, but it gets the job done and doesn't feel different on the head (pressure).
I just got tired of always pushing the leather back, and if I will decide to return the headphones for this reason, it will be towards the ending of warranty, in one year. Maybe by then they will fix the production.