emailed few mins ago, been in chat all morning and ive tried calling no answer.
so far im out 2-3btc because of the wait.
They aren't perfect and depend on btc exchanges API's, so issues may appear sometimes. Have patience and they will solve your issue quite fast. Make sure you keep a balance on the exchanges, if you do arbitrage between them, so you can mitigate any bitinstant delays.
Disclaimer: I'm not affiliated with Bitinstant in any way, only know what it feels like to monitor a forum to find you customers issues.