I am not sure why you have been denied support.
Yes, if you need assistance with the migration itself then this is a payable feature; however if you experience an error like you do, then it is my believe that you are entitled to support.
If pkh suggestion did not help or you are experience another error afterwards, then could you share your case id if you got that far or reply with the current status here.
That's a good idea. I initially opened a case just to ask a few basic questions about the process prior to running it and that is when they hit me with "You will need to pay". I did not try to open a new case with the error that I am getting. Thanks!