Asset Care Inc. I'm receiving harrassing phone calls to a wrong number! Wilmington Delaware

For over a year I have been receiving daily phone calls from Asset Care Inc., on my cell phone. When I answer, I receive a recorded message saying they are attempting to collect a debt, and giving a phone number to call. When I miss the call, I receive a voice mail that is similar in content.

I believe that I am receiving these calls in error for the following reasons:

I do not knowingly have any outstanding debts.
I have never given my cell phone number to a creditor.

At the beginning, I attempted to call the number, but was left on hold forever. I realized this was futile, so I no longer try to rectify the situation this way.
To add insult to injury, my cell phone is a pay-as-you-go phone, which means that each of these nuisance wrong-number calls costs me money! I am also unable to block the incoming number.

I've complained to the FTC, FCC and my state's attorney general. So far I've only heard back from FCC, telling me they're the wrong agency to contact. FTC's website says they don't respond to individual complaints, just maintain a database for law enforcement agencies to determine whether action is warranted.

The obvious solution is to contact Asset Care directly, which I'm reluctant to do because as of now they only have my cell phone number, not my name or address. Am I being paranoid? So I'm pretty frustrated.

Martha
Scottsboro, Alabama
U.S.A.