My ticket was refunded within two days after calling the Hudson and talking to a very nice agent.
I did try to call right after I received the email letting me know that they had rescheduled my ticket for a May 2021 performance, but as others have posted, it would ring once and then go to a busy signal. When I did get through after hours to a voicemail, it told me that I could email inquiries@spectrumservicesusa.com, so I emailed my refund request to that address. The next day, I tried the line again and was placed on hold for 24 minutes, then the call failed. I tried again, and was only on hold for a few minutes. The agent promptly and courteously processed my refund request. Two days later, I received a nice email reply to my email message, and it mentioned that it looked like I had been able to get my refund taken care of already. That same day, the refund posted to my credit card.
So for those of you seeking a refund, you can try emailing to the address I mention above.