Once the funds leave ZipZap or whoever cycles it for you it's out of their hands. 

Be VERY careful!  After you click send its done.

I actually feel kinda bad for ZipZap.  I'm sure they're getting the brunt of the complaints that frightened people are having with BitInstant by mistake.  If ZipZap is smart they'll cut ties with BitInstant and let BI scurry off into obscurity.