Had 2 RT tickets from TLV to EWR and ORD with UA on the outbound and AC on the inbound (UA stock). I recently checked and turns out AC changed both tickets by just over 2 hours. I called United to rebook on UA 90 (price was obviously more expensive). 1st rep said I can only rebook on AC, no refund option. 2nd said I can rebook on AC or get a full refund, but can’t rebook on UA. After 2nd HUCA, finally got rebooked on UA, they even allowed me to change the date 14 days before/after original flight with no fare difference.