language barrier is the main cause of issue.
flew iberia j from tlv-mad-jfk a while back. 4 avios tickets and one lap infant. now, before everyone barks, there were plenty of open seats for the lap child on both legs. saved money/points booking this way. very difficult to stress urgency of complaint/concern with the spanish especially when was looking for comp for lack of ksml and other customer service issues. horrible customer service. language barrier and comprehension major resistance. cant stress that enough.
imho i dont think you get more than what they are offering because they seem to just offer comp, and then shut the case. maybe someone from the parent gives more attention but a social media storm wont do much in this case, especially with all the unanswered questions about lack of boarding etc...