Originally Posted by Often1

However, if all you want is a refund because your flight has been cancelled or you have been auto rebooked onto an unacceptable routing, the COC entitle you to a refund. Thus, no need to torture yourself. Let it go and deal with it after the fact when the lines are clear or you have to be at a US ticket counter anyway. Needless to say, your refund will be delayed at least by the time you delay, but it is well worth it. If you really want to protect yourself, send a webform complaint to US noting that you attempted to call before the scheduled departure time, but could not get through and would like a refund. It won't do much but make you feel less stressed.