After almost 2 weeks I received a reply:

We found that a record of sale does not exist for your travel ticket number xxxxxxx. Upon verification of the sale of this ticket number, we will promptly proceed with your claim.

We request you to please contact after 10-15 working days.. Be sure to include your ticket number on your correspondence.. Once the ticket record is set up in our system we will further investigate this matter further.

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We appreciate you choosing United Airlines and hope that we can welcome you onboard again soon..

Regards,

XXXX XXXX


I purchased the ticket about 4-5 months in advance. How can they not find it?
United Airlines Passenger Refunds