If you have access to a good travel agent see if they can get the refund policy for refundable tickets. I used to have it but it's not current.
Although tickets are valid for travel for one year, refundable tickets in the past could be refunded long after they expired for travel. I think up to a certain year, refundable tickets were always valid for refund, without time limit. At a certain point, I think UA began imposing a refund time limit for refundable tickets. Initially this was several years but I think it's been reduced over time and there may now be a fee to process refunds on refundable tickets more than one year old.
Even if you can't get a copy of the policy, keep persisting with customer service and the refunds department.