StubHub review: Selling listed tickets after 3 cancellations/reschedules

I listed tickets for sale on StubHub in January or February of 2020, for a concert, Country Thunder Florida, that was originally scheduled for March 19-21, 2020. The event has subsequently been canceled / re-scheduled 4 times to 3/27-29, 2020, October 16-18, 2020, March 19-21, 2021, and the most recent change to Septemeber 10-12, 2021. In August of 2020, the event sponsor provided for an oppurtunity for ticket holders to receive a refund based upon the uncertainty as to whether this event would ever occur and financial hardships many people experienced as a result of the Covid 19 pandemic. I elected to receive this refund but failed to check to see whether my tickets were still listed on StubHub. I had also listed tickets for this event on another re-sale website (Vivid Seats), and Vivid Seats canceled my listing when the original scheduled concert dates had passed. It came as quite a shock when I was notified by StubHub via email on February 17, 2021, that my tickets had been sold. At this point, I no longer possessed valid tickets for this event. StubHub policy in this situation that the seller may be charged for the full amount of what they would have received, as a result of no longer having the tickets. I spoke to StubHub on 2 occasions this past week to try and resolve an outcome for me that would not make me liable for the full amount of the tickets, due to the circumstances of the Covid 19 pandemic, and that this listing should no longer have been a valid one after 4 re-schedules of 18 months in duration. On both occasions, the StubHub representatives indicated that there was nothing that could be done to reduce my financial loss in this matter. I would be willing to pay some inconvenience/re-stocking fee that would be significantly less than what StubHub indicates that I am liable for. I have no doubt that StubHub will have little to no liability to the buyer of my tickets, and their collection of my monies constitutes a predatory practice in light of the policies of other ticet re-sale companies that cancel ticket listings that are canceled/re-scheduled. As I previously mentioned, I am willing to agree to paying some fee for my oversight of checking to see whether my ticket listing was still valid. Any help with obtaining a resolution will be greatly appreciated. I can be reached by email - bob. [protected]@gmail.com, or phone at [protected].