I 2 bought t tickets from United airlines in December 2015 for travel on Feb 2, 2016. I had to change the flights. The newer tickets were much cheaper. So after paying the change fee, United said they will bank the remainder and I can use that for future travel within 12 months.

Now I call them, and they can not find that reservations. I have the original, changed receipts and credit card statements. How do I proceed? They will not let me talk to the supervisor, I tried three times.

Thanks!