THe police department is tough...that is, it is tough to sue the police department based on what you describe.
The best cause of action would be under 42 USC 1983, the civil rights
act. This is federal law that can be used to sue a government body (like a police department) for violations of civil rights.
Here is the law
Every person who under color of any statute, ordinance, regulation, custom, or usage, of any State or Territory or the District of Columbia, subjects, or causes to be subjected, any citizen of the United States or other person within the jurisdiction thereof to the deprivation of any rights, privileges, or immunities secured by the Constitution
and laws, shall be liable to the party injured in an action at law, Suit in equity, or other proper proceeding for redress, except that in any action brought against a judicial officer for an act or omission taken in such officer's judicial capacity, injunctive relief shall not be granted unless a declaratory decree was violated or declaratory relief was unavailable. For the purposes of this section, any Act of Congress applicable exclusively to the District of Columbia shall be considered to be a statute of the District of Columbia.
But it is tough since to prove violation of your civil rights you need to prove that the police improperly arrested or detained you. If they did? And you can prove it? THen you can sue for a violation of your civil rights.
You would need a lawyer to file this.
As for the repo guy? That may be easier. If they lied about you, you can sue them for defamation
. If you can prove that they lied about you and that lie harmed you, then you can sue for the damages you suffered