Car hire companies ? a possible scam

I wonder if anyone else has used or has experience of a Car Hire Company called Self Drive African Car Rentals? I believe they are also associated with The Safari Company, both based in Johannesburg. We have rented vehicles in S.A twice before without any problems, but not with this company. We picked them because they offered to deliver the vehicle to Harare Airport for us. It all looked very good, their web site is excellent, lots of good endorsements and our correspondence with them was responsive and professional. However since we agreed on our requirements and paid a deposit over 3 weeks ago for the car hire we have heard nothing from them and there is no reply to any attempts to contact them, emails, messages left on answer phone. We are wondering if we have been 'scammed', but the web page is still up there and looking good. We'd be grateful to hear from anyone else who might have used this company.