Like you, I’ve been waiting for a response from Udemy for the same problem for a month now. After contacting “Udemy Support”, I finally managed to get a response from Udemy, but it’s still not solved.
Finally, as a solution, I wrote to the “contact” section of the gamede.tv website and described my problem in detail, indicating the name of the Udemy course, what I paid for, what the current error is, etc. They asked me to create a course account on gamede.tv and send them the link to my account. Now, thanks to them, I can access the course through gamede.tv instead of Udemy.