I have read a recent letter from HealthNet that seems to be the same one above. The one I read was a form letter that said that personal information may have been stolen. I cannot speak for Debix, as I am not familiar with them.
If there is a theft, the letter I read discussed insurance coverage for incidents that occur as a result of the theft. If the coverage does not pay for any potential loss, you should consult with an attorney regarding your possible claim against HealthNet.
Also, see Arizona Rules of Civil Procedure 57.1 and 57.2, which deal with identity theft and civil lawsuits.
Legal Disclaimer: I am not your attorney. The only method of establishing an attorney--client relationship with me is by a retainer and fee agreement signed by me, which is not offered via this site. The information given is not legal advice and is for general information only. My answer is limited to the facts presented and may not be complete or applicable to your situation. My answer is given upon the condition that you will contact an attorney licensed in your state to receive legal advice that applies to your particular situation.