CB Richard Ellis Security Deposit Refund Internet

I paid a security deposit of $3,935 dollars on Oct 2005. I ended my lease on April 30th 2012.
I received a check for $338.43 as my security deposit refund dated May 8. I asked for a breakdown of expenses that I was being charged and was told it is being sent to me, well today is May 21 2012 and I still have not received any explantation of what/why of this amount. How can a company not have this information and send along with the check is be on me. I have had numerous complaints over the years and very poor response. This company is a total ripoff