Payment made and nothing received. Poor service.

I ordered a part for my Amarok which I paid via eft and I was promised it would arrive roughly 5-7 days later via PostNet. Its been over 2 months now, nothing arrived and they are not sure what happened to the part and couldnt give me a reference number for PostNet. I requested a refund and they promised it would be in my account asap and still nothing has been paid into my account. They now don't take my calls or get back to any messaged left. VERY POOR SERVICE.