Have you contacted their support?
indeed, i have contacted support before posting here. they told me - "During upgrading system, withdrawal to other available address on USD platform will be restricted". but i would like to know maybe where is any tricks or something...
So this means that they are upgrading their system and have with held your transaction. Sometimes exchanges put a hold on our transactions to safeguard our coins from any loss. By the time now I think your transaction would have been completed. Can you update us by telling what happened after that ? It would be a good info for others as to what to do in such situations.