Said it's a serious matter and asked to call back.

I didn't answer

Academy Collection Service is scum of the earth. My wife has power of attorney for her mother who has only Social Security. She on Medicaid and lives in assisted living. She had a debt from CitiBank shew is unable to pay off except at a rate of $10.00 per month. These [***] harass us day and night. We have both faxed and mailed numberous copies of the power of attorney and documentation that my mother in law has zero assets and virtually no disposable income each month. Yet they persist. Thewy use different phone numbers to call from, and it always shows up as "Caller Unknown" on the caller ID. Even when I've been desperately sick the call as late as 9:00 PM.

There should be a way to stop such harassment. We are not responsible for my mother in law's debts. CitiBank was stupid to give her a cash advance to buy a used car when she had no income. Greedy [***] who deserve what they get.

they call the wrong number and i told them but they still call.....how to block them....help

If a collection agency like this calls you and they are trying to reach someone else you can file a complaint with the FTC.  You can go to their website at www.ftc.gov and file and complaint using an online form.  I used to work as a contractor for the government and I know that the more complaints you file against this company the better.  Usually government agencies consider your complaint like a "vote" and therefore the more complaints they get against one company, the more likely they are to act on them.  I would file a separate complaint for each call you receive from them.  The calls should stop.