Work Service SIP

Dear partners,
please be aware of Work Service SIP.
They used our Peru and Colombia CLI and BD NCLI routes and after it asked for a payment. They are not replying to any e-mail or Skype or Whatsapp from last 1 week, the amount is 1800.00 USD. Its seems they are not willing to pay.
We request to you if you don't want to be cheated, do not work with them. And if you have any business with them please share with us for an offset.