I'm sorry to hear that. Obviously you'll want to contact EBay/Paypal, as they say they offer some level of support in such cases - though the reality may be somewhat different. Also see what your credit card company has to say (presuming you used PayPal). Talk to Consumer Direct too, though I believe they are generally not much help on EBay matters.
If it was a 'Buy Now' purchase you would have been covered by the Distance Selling Regulations, except these are difficult to apply to rogue traders and you need to reject the items pretty smartly (and not send them for repair since that could be considered as "acceptance" of the goods).
It seems to me that much vintage Contax gear offered on EBay is potentially dubious, and this is particularly difficult to spot in the meagre photos and descriptions. Personally I'd leave all older Contax gear well alone unless it's offered by an original owner, who provides a name, address and phone number, etc.
Finally, is the camera repaired? If it is, then I gather that a good Kiev is potentially still a good camera ... but that may be little consolation.