I was trying to purchase FRA - EZE on LH. I saw it on united.bomb for around $1400 (B Class). I tried booking it on the LH website directly it priced out at over $5000, full fare Y. I called them, they told me that they had no B or lower fares for my selected day of travel. I then went back to the UA website and purchased 2 tickets. How can this be?