Payday loan collection agencies seem to be notorious for breaking the law. I think it's because payday loans are very cheap to buy (pennies on the dollar) and anyone can buy them. They then are free to do what they want and they keep whatever they can collect. The "companies" that purchase this old payday loan debt, are often not legit. They will call people up pretending to be lawyers or law enforcement saying that they have committed a crime and they will be taken to jail if they don't pay.
Some say that you have a pending lawsuit against you. All of this is garbage. If there really was a lawsuit against you you would have a process server or sheriff come to your door and give you papers. No one is going to call you ahead of time to let you know your going to be sued. I am still waiting for legal papers after a supposed legal document company called me and said they would be at my house or work tomorrow which was over 2 months ago. You have to remember not to get nervous. These people are jokes so just laugh about it.
Legit collection agencies often collect on a contingency basis for their clients instead of purchasing the debt. These are often fresh accounts that have a good chance of being recovered. When you purchase debt it is often pretty old and you find that some of the debtors either went bankrupt, have already paid this debt, or are no longer living at the address and phone number provided. Skip tracing is involved and the debts have a much less chance of being recovered.
There are legit collection agencies that do purchase debt because they can keep whatever they recover. Companies that you can purchase debt from usually don't check the person out who is buying it so this makes it much easier for companies that are not legit to purchase them.