Unethical behaviour - Retaining full deposit as fee

Solo Properties recently assisted in finding a tenant for my property and it was verbally communicated to me that the fee for finding a tenant would be half of 1 month's rent. Once the deposit was paid into their account (which was a full month's rent), they held on to the full deposit, including the key deposit and did not pay a cent into my account.

I did not receive any documentation to sign to agree on a full month's rent as the fee to Solo Properties hence there is no agreement to state that they would take a full month's rent as their fee. Other agencies were charging half of a month's rent as their fee.

The way this company does business is unethical. Please do not use them.

Solo Properties, please provide proof of any agreement between you and I on the fee to be charged.