VODAPHONE TABLET NOT REPLACED

Hi, i saw a great special of the Vodaphone Tablet and bought 2. First one started giving problems and i sent it back and it was replaced now the second one started with same problem and i send to Wonderpark Mall for repairs. Then they phoned me after a month to fetch it but it was not fixed and the the Sales person could not even explain what the Report says worst of all it now had scratches as if i was thrown on the ground. Then i complained and the Sales told me to relax cause they take notes of the items when they receive them and definately it was not scratched when i brought it in. Now i want Vodacom to explain how they replace one and cant replace the other one??? Now im paying for the Contract of which the Device cant be used ? ? With 4 different Accounts i have with Vodacom how do they even treat me like that ? ?