As others note, many carriers have dropped the requirement of requesting refunds from third-party vendors such as TA's, take over the ticket without fee and then cancel and refund. CX apparently has not. A pity because by taking over the ticket and refunding, carriers emphasize -- for the future -- the value of booking through the carrier.
If there are multiple operating carriers, you will need to turn to the ticketing carrier in the first instance.
All of this points to the value of a chargeback as the backstop. It leaves the consumer out of the internal workings of the transaction.