I would suggest calling Vodacom and giving them the IMEI. They will be able to check if the device is stolen and the IMEI has been blacklisted.
Also ensure that the imei on the sticker under the battery looks original and has not being wiped clean. The first thing they can do with the stolen phone is change the IMEI(its illegal) and wipe the sticker clean. If it is like that, stay away.
Also, try and get a small contract signed up between you and the seller that says they are selling you the phone and make not of the IMEI, model number, etc. Also get a copy of the person's ID.
You got to be very careful. Better to buy brand new. Or importing one from China or America(Ebay). At least those guarantee your money and Paypal will refund you if the device is faulty on arrival or you find out it is stolen. Plus a lot of the Blackberry's from China(Original Blackberry), are refurbished so come with new housing and new screen. Not half bad. PM me if you are interested and I can try and find the model you are looking for for a good price and can advice on it.
Regards
Kavir
