Ask the airline to confirm that the ticket was cancelled, and the date and amount of the refund that the airline issued to the agency. That should be all you need to obtain a refund from the agency.
I gave the travel specialist the date and time of when the ticket was cancelled. I also asked if they had reached out to the airline and got that also. They confirmed that they did and that it shows that I didn't cancel within 24 hours since it was a WHOLE DAY and HOURS ahead of what I told them. You would think that they would look at the time zones and make adjustments, but NOPE. They're incapable of that. So a few days ago, I chatted with customer service for the US based airline and asked for the time/date that it was cancelled and also for them to give it to me in PST. Well what do you know..... They gave me the time in Zulu time that the travel agency got and converted to PST and it matches exactly what I have been trying to tell the Chase travel specialist. I just submitted that to the travel agency and still waiting for their "back-end" team to review it.