A FAULTY TABLET

I took a tablet with Vodacom in April last year. The device started giving me problems in March this 215. I sent it to Vodacom/ Vodaworld for repairs on 30/04/2015. I then collected it on 29 May 2015. 6 Days later the device started giving me the same problem. I then returned the device back to Vodaworld on 11/06/2015. I collected it 6 to 7 days after they confirmed it was repaired. A month later I am still sitting with a tablet with the same problem I sent it for, for repairs all along. Now I am paying and I am sitting with a faulty device for over 36 hours now. It doesn't help me to be returning this tablet back and forth to Vodacom without a solution that is permanent. I am now even thinking that this device was passed to me after it was repaired from someone else. I really feel I was not given a new device. It cannot be faulty over and over. I really need a functioning device or I should be forced to cancel this contract really. This is just too much