PayPal - **** or legitimate?

I advertised a product on internet. A prospective customer expressed interest. He suggested we make use of PayPal. I agreed to this, although I have not used them before. I was also requested by the buyer to make payments to them for the collection of the article. The buyer covered these amounts by depositing equal amounts into PayPal for me to receive with the cost of the article. This process continued until I deposited R16.500,00 over to PayPal. I was then told by them that I needed to pay over an additional R7000.00. I refused and cancelled the sale. I requested PayPal to refund my money. They refused and do not reply to my emails.