Recourse for deposit return?

I'm sure someone on this board can help direct us to someone or agency to help us get our deposit back from the letting agency.  We moved out on May 1, 2007 and had our checkout inspection in our house with the rep from our letting agency.  She signed off on everything and told us our deposit of 850 pounds would be in our account within 10 days.  Well long story, short....it isn't.  I have been in contact with the letting company for the last 6 weeks and they keep assuring me that the deposit will be there within the next 3 business days.  It still isn't.  What recourse do I have?  Who can I contact to help me receive my money?  We are back in the US now and so that makes it even harder to deal with and I think they know it.  We have kept our bank account open so they can just make the deposit.  So not sure what their problem is.  Thanks for any advice.

Just a follow-up now that our problem is finally resolved!  I got a nice email from a friend who suggested I contact the ARLA (Association of Residential Letting Agents) with my problem.  So I did and sent copies of my correspondence to the letting agent as well to show that I had contacted ARLA.  I went ahead and filled out the 4 page report to send to ARLA and was in the process of making copies of all my correspondence with the letting agent when lo and behold, the deposit made it into my account finally.  So for those in the same situation, it's nice to know that there is someone to turn to that might keep these letting agents from being bullies in the future! 

Yeah it works if the letting agent concerned is a member of ARLA.  Un fortunately some of the more unscurpulous ones aren't and then your only recourse is through the courts. Anyway glad to hear you got your money back, that's great!