Mutui e Prestiti .com s.r.l.

Hello there,
Please be careful from Mutui e Prestiti .com s.r.l. and its owner/ceo Mr. Passario Elia. He made a VoIP traffic with us (LinkUP s.r.l.s.) between October 2015 and April 2016. I invoiced that traffic in June 2016 and now, September 2016, he refuses to pay the bill for € 858,73 looking absurd excuses, like <<I don't want to pay the traffic of my Telecom fixed number. Please give me the invoice without Telecom traffic.>> (but it is just a CLI), and pretend to have the evidences from my provider (so he get the name of my providers).
It also appears to be in business with an another company named SINCROLINK S.R.L. where it seems to sell Internet connectivity and other services in the IT area.