If you want to complain about your estate agent then you can do via the Property Ombudsman.
His powers allow him to make awards of compensation for financial loss and/or aggravation, distress and inconvenience, where he feels it is appropriate. The service is free of charge for the public.
They can deal with lettings as well as sales issues!
Fantastic! Your estate agent must be a member of an Estate Agents Redress Scheme! It must be a scheme regulated by the Office of Fair Trading and have the power to investigate complaints.
If you have problems with your estate agent then have a look on the property ombudsmans site to see if they can help!