Poor management by Agency

The agent miss-informed me regarding the mandate and was unclear how the commission was calculated. Informing me that I was free to find my own tenant but they'd help me find someone. I found a tenant who paid the deposit. When the agent found 3 tenants she got them to sign the lease and told me that the mandate was binding and because they had signed I had to refund my tenant her deposit..this was at month end-leaving my potential tenant with having to find a place at short notice -making me look very bad. I was often unable to get into contact with the tenants to do repairs. I wasn't informed in time to find a new tenant that the tenants had given notice I only found this out in the middle of the month after phoning the Agents that the tenants were vacating the premises.Tenants failed to give 20 working days notice as is required by law.Yet the agents refunded tenants their deposit..making me loose this.The agent were rude and disorganised losing my keys which I had organised to pick up -when I got there they could not find my keys and gave me someone else's set of keys. Remote and keys were collected from my house which they deny. Poor contract has since been changed.