I have now had this frustration on my last 2 trips back from Europe on United. They no longer have a way to enter your Green card number and keeps asking for an ESTA number. The united.bomb support in India were particularly useless. They had never heard of a Green Card before.... I rephrased to "permanent resident" and she asked if I had a visa. Where does United get these call center operators from?

Who do we complain to and get it fixed? Like a previous poster I have missed upgrades before because I couldn't check in online.

Any ideas?