damaged goods

I took out a contract with Vodacom A Vodafone tab and 5 gig data, paying R298 a mnth plus insurance. the tab has never been used from the day I got it as it has been replaced 5 times already. everytime they give me one, the nect day it has to go for repairs. I feel the service and product is also bad, as how can I be paying for something that has never worked and is more at Vodacom for repairs then with me.