Avoid buying from Ben Ali

I was looking to buy a new ice machine so I found this man advertising on Gumtree. I contacted him and explained that I wanted a new ice machine but that I would like to trade in my existing machine. He agreed and we came up with a price of R15000-00 plus my ice machine for a brand new bigger ice machine. He sent me an invoice and I paid him the R15000-00 on 2016/01/11. Directly afterwards, I got a mail telling me that he no longer wants to take my ice machine and therefore I have to pay him an additional R6500-00. I told him I do not have that amount of money and that he must please return my R15000-00. I am still waiting and he no longer answers my mails or my calls. I have made a case at the police and I have informed both banks involved. He gave me an address in Springbok but the police there tell me that that address does not exist. I have traced his IP address and it registers to a place called Mountain View in California, USA. DO NOT buy anything from this person. I have reported him to both Gumtree and OLX.