Deposit refund refusal

I was a tenant for a year with this estate agency. I am very disappointed that I did not give them any issues yet when it was time to refund my deposit it was held back. This all due to a dispute with the owner that they have where she was supposed to pay them the placement fee. Further to that after being informed there is no renewal of the lease they still sent me a rental statement which was ***** as they had no authority to collect rental. So after a back and forth with the owner the owner informed that she will not pay the placement fee and they need to refund me deposit. They have also agree that the placement fee is an agreement with the owner therefore I’m not part of that agreement. I would not recommend this estate agent to anyone as they don’t have fair practices.