WiFi device faulty, again

I booked my Wifi device in at the Data Store in TygerValley a week before Christmas, I dealt with Mornay. This was the second time that I have returned this device to Vodacom, the first one was replaced as it was faulty. I did not get any feedback from Vodacom and went back to the store the first week of Jan. I was assisted by Dewan who promised to contact me, I provided my cell number and e-mail. I requested that the contract be cancelled. I am not wiling to pay for something that is clearly not up to standard. I never heard from Vodacom or Dewan again. I went back to the store on Sun, 1 Feb. I dealt with Mornay again and again the WiFi device was faulty and replaced. According to Mornay Vodacom has been sending me notifications to the number for the WiFi device! This after I have given them my cell number twice. I requested again that the contract be cancelled, to which I was told that he is not in customer service and I will have to take it up with them. Mornay sent and e-mail to their CS dep and again got my number wrong, at least I was copied on the mail and could follow up. Chantel from their CS dep contacted me on Monday, 48 hours later and I still do not have an answer.