I flew UA EWR-TLV. 2 adults and 7 kids. I booked my tickets months in advance, and with premier had my economy plus and bulkhead booked. At checkin the agent said she has some issue with printing my infant ticket, and she needs to fix it. it took her 2 hours and calls and supervisors to finally get me my boarding passes, but by that time it was already within 60 min of flight so our seats were given away already. Due to whatever she was trying to do, she canceled our reservation and rebooked it, so it didn't have mileage number, so we didn't get tsa pre or premier printed on the boarding pass. Security line was terrible, and we begged them to walk us thru the line but they wouldn't. They did hold the flight since our luggage was onboard, but when we got to boarding they told us they have individual seats all over the plane, which means my 3 and 5 year old sitting alone between strangers. And since we werent in our original seats, they gave away our meals to others, so we didnt even get food.
Whats the best way to request compensation and what can I expect?