FFS - sorry to hear your story Florian. Doesnt sound like you will get them back.
It really sucks when you cant put anything down - even for a minute.
I had a pair of sunnies pinched off the roof of my car at Woodies while I was right there getting gear out & sorted. Turned to put em back on when Id sun-screened up and they were gone.
Makes for really sh1tty feelings about who it might have been. Luckily when my sunnies walked there were lots of randoms & fishers around. Surely kiters wouldnt hit on kiters - you gotta hope it never gets that bad hey.

If you see some fat low-life sporting a super cool pair of Seabreeze sunnies - they are probably mine

Bait the buggers with an old board and a good length of fishing line attached to your towball, watch them go arse over when they run out of line at full speed halfway through the carpark. Not that theres much u can do to them them, surely u can scare hell outta them tho, let them know about it. Maybe take a phone book? they dont leave marks!

I haaaaate thieves