The main law that applies will be ARS 20-445 (part of the AZ insurance Code). Here is the law
No person shall make, publish, disseminate or circulate, directly or indirectly, or aid, abet or encourage the making, publishing, disseminating or circulating of any oral or written statement or any pamphlet, circular, article, sales material or literature which is false or maliciously critical of or derogatory to the financial condition of an insurer
, and which is calculated to injure any person engaged in the business of insurance, or any domestic corporation or group being formed pursuant to this code for the purpose of becoming an insurer. This provision shall not be deemed to restrict the right, lawfully exercised, of newspapers, magazines, radio and television stations, and similar public media for news dissemination, objectively to publish and disseminate news.
As you can see, the above language is regulated...so you can report this to the State Insurance Commissioner.
And request that they take action for this improper conduct.
This is a separate action from the civil action
of defamation...Defamation is defined as a false statement communicated to another person that damages your reputation by exposing you to hatred, contempt, or ridicule from other people. Libel is communicating a defamatory statement by writing or picture. Slander is defamation by oral or spoken communication.
To sue for defamation, you need to prove "damages"...that the person (or in this case company) was harmed by this false information. TO prove damages you need to prove that there was harm...so if the prospect refuses to retain the company based on this false information, then the company would have a defamation case.
Let me know if you have more questions