When still known as Academy Collection Service, this agency in November 2008 was spanked for $2.25 million by the FTC for chronic violation of debtors' rights. This remains among the highest penalties ever handed to a debt collector. Shortly thereafter ACS rebranded as Monarch Recovery Management. It did not take them long to attract a new batch of Fair Debt lawsuits since then. ACS or MRM or whatever name it likes needs to be sued by each of you it decides to abuse.
Nationwide Debt Collector Will Pay $2.25 Million to Settle FTC Charges [press release]
Official-type material on US federal collection law: