I got the same call I blocked them and now they are using different numbers

They keep calling and changing numbers when I block them
This message is intended for #####. This is Sarah Wilson from the Federal Investigation Department. This message is to inform you that there is a legal case filed against you and there is a warrant issued for your arrest. Before anything goes wrong I want you to give us a call the department call back number which is 9044251757. I repeat it's 9044251757. If we don't receive any call back from your end we'll have to proceed against an illegal way. Before we do so make sure to give us a call back. Once again this is Sarah Wilson from the Federal Investigation Department

Harassing phone calls about a Payday loan I've never received or requested. Threatening legal actions, and extremely rude.  I explained several times I have not received nor applied for a payday loan.  Asked them to stop calling, but they keep call several times a day threatening legal actions for a loan I don't even owe and never received.

They won't stop because as long as you talk to them they think they can harass you into paying to make them go away.  This is called extortion.  Tell them what the law says and file reports:

Federal law (FDCPA) requires them to send you a letter (US MAIL ONLY) postmarked within 5 days of their first contact that contains their name, physical address, the creditor’s name, and the amount of the alleged debt.  It also must contains “mini-Miranda” telling you that it is an attempt to collect a debt and that all information will be used for those purposes.  The one other important thing that this letter must also have in it is that you have a right to dispute the debt within 30 days of receipt of the letter and if you do so, all collection activity must be stopped until the debt is verified.

Read up on your rights here and also make a complaint at this government site:  http://www.consumerfinance.gov/

Also file a complaint with your State Attorney General's office.
List of State AG’s offices:   http://800notes.com/faq/attorney-general