I am having the same problem with Bitstamp. I have made a sizable deposit which they have confirmed receiving, but will not give me access to it, and have started additional KYC even though I have already handed over personal details such as passport.
I have now provided them evidence of where the money came from, although I don't think this should be required. My funds still remain tied up, with support response times of longer than a day to each individual message.
Note that each additional reply made to a support message puts it at the end of the queue, so no proper dialogue with support is possible:
"Please note that if you reply to your own ticket this "bumps down" your ticket as our system is designed to give older tickets priority over the more recent ones.
Best regards,
Toma Bertoncelj"
The support team is severely understaffed, and no live chat support is in place.
I have now been waiting 4 days to get access to the funds since they were received by Bitstamp, even though I had already complied with KYC requirements. I disagree with the level of questions asked, and the process should have started at the point the deposit is initiated, not received. It smacks of a site that is simply trying to cover their own asses rather than serve their customers to the level deserved given the amount of money in question.
Let this be a warning to anyone considering using Bitstamp, I will personally be seeking out a more professional site, if one exists.