You just fell into one of the first and hardest lessons that new landlords learn.
No agency is interested in getting you a good tenant..they just want to put someone (anyone) in as quick as they can so that they get the commission and run.
Sorry to say, but unless you are tightly controlling the agency, you will lose.
If you use and agency, you have to require a written contract that requires the agency to provide to you the report from the background/criminal/credit check. You must reserve the right to select the tenant yourself.
There isn't anything you can do now.
I am sure the agent knows it is a bad tenant. I am equally sure the agent doesn't care.