Late reply, but just had a similar experience. The website seems to only allow a paid option, worse than that, it is only offering cake and prosecco. I tried the Facebook messenger option a number of times, and received no reply period. I tried it the other day at around 11 p.m. local time in Europe, sending my confirmation code, passenger name's karma and the request for kosher meals to be added to all flight segments. within minutes I had a reply from an agent saying she had taken care of it, and when checking in for my flight today, lo and behold, the kosher meal request is there for all flights segments