I called Delta initially to cancel April 3, just the basic US phone number and received a confirmation code. Got a little tense as DL phone reps would insist that a refund was initiated and I continue to wait but then could find no record in their system to verify that it actually was in the works and ultimately my period to initiate a charge back expired. My understanding is they had some sort of internal complication between Priceline and AF that voided my April 3 code but never initiated a new one. I became an example of the squeaky wheel gets the oil. Took some effort but 3 phone calls per week for a month got it done...just had to win the lottery and connect with a competent agent. There were many times when DL agents told me to call priceline or AF but that is incorrect.