Holding Deposit kept by Landlord

We started the renting process at a 4 bedroom house for students. We signed the tenancy agreements and paid the holding deposit of one weeks worth of rent. After a fallout between one of the tenant and the landlord, the tenant decided to not proceed and we started looking for a 4th person to replace him. The landlord agreed and gave us time, but after finding someone and informing the landlord, he said we lost the house. He did not inform us prior to that. According to the description of the house advert the landlord has to refund the deposit since it was his decision to not proceed. How do I get the holding deposit back?

first tell him you want it back and if hewont do it . Tell him you will sue and raise hell with the council. , also put his windows …

Colin you starting trouble lol

forgot to finish" put his windows… in lockdown"

From your text text it sounds like its the tenant that decided not to proceed. If its a joint tenancy then finding a 4th person would make it a different tenant. However, if he agreed in writing to give you time to find someone else or if he held the deposit for more than the statutory 15 day limit, you may be able to claim the deposit back. If he refuses, contact Trading Standards.