No response whatsoever to payment queries

almost 3 months ago i completed and posted a HSE file from JHB to PE for DMD 10 Telecoms with a COD arrangement after receiving the file I received a thumbs up mail about the file and was told my money would come in after the month end payment of a client. To this day i am still waiting on my payment. They do not respond to my calls, sms's or emails even after i put in place a late fee for everyday payment is further late... I really don't know what to do anymore