AVOID! They are scammers.

I responded to an ad on Junkmail.co.za. The seller - Hi-Tech Mart - seems legit and communicates well initially until payment is made. Then an unknown courier mails you on the day of delivery, asking for a large sum to be paid as 'temporary insurance' which 'will be refunded'. The problem is the banking details for this courier is the same as Hi-Tech Mart!!! The courier is also no-where to be found on the net. No website, no facebook, nothing on Hello Peter. The moment i started asking questions and explanations, phones got put down in my ear, and my calls screened. Avoid these scammers!