No money back from their investment

I deposited my money last month for 20days interest, when it was matured I did not get even a cent out of R1500 that I deposited. It is said that you receive your money with interest within 3days (72hrs) but its now 2 full weeks. I sent the deposit slip as it was mentioned and I sent 2 emails to their [Email Removed] address but till today I haven't got any response from them. The maturity date is 2 weeks back. Please advise how I can get my money back as their promises of another R1500 interest is a vain. Their investment is not professional. Please try your best when working with people when you really mean that you are investment company cos even my brother got half the other half is not paid.