If your landlord does not protect your deposit by using a tenancy deposit protection scheme, or won't tell the you which scheme they are using, you can take them to court.  The court can order the landlord to pay the tenant THREE TIMES the amount of the deposit as a fine.

source: www.direct.gov.uk 

fairRenting.com - a way to get reliable legal tips on how to try and ensure tenancies run as smoothly as possible.

First - If you're having a tenancy problem, check out my advice section. It's full of handy information like the one at the top of the page. Its broken down into sections to help you find information quickly, whether you're a tenant or a landlord.

Second - If either the tenant or landlord refuses to play by the rules in that advice section, register them on the fairRenting.com properties database and help others avoid them