demand for payment

I received a email from Mr. William Davis  <william.Davis@thecashinsta.com telling me that I owed for a pay day loan in the amount of $912.74.  Mr. Davis told me to call this number 347-332-0189 to get the matter solved.
If payment is not received by August 31, 2018, they will have to do whatever they can under the law to recover our money with accumulated interest from me that includes but not limited to legal proceedings against me......