Yesterday I contacted with GMAC on behalf of my friend. He went to Taipei test center on 9/29 but it did not open.
As we know, "the change" is coming. So I suggest u guys that if u also have this issue, just contact GMAC in US directly without sending email.
I successfully registered for my friend on this Friday afternoon.
As I know, there would still be several spaces on this Friday and next Monday. Even today's night is also available.