Hi I'm from Malaysia and will be enrolling at the Univ of Colorado. I don't know much about visa application, as my I-20 hasn't been posted yet. But from what I know, once you receive the I-20, and provide your supporting documents (like proof of financial support etc), then it is just a matter of going to the US Embassy for the visa interview.
As for MACEE, I have only contacted the KL branch before, and my calls were answered. Maybe you just happened to call at a bad time.
Hope this helps.