I can't return a faulty laptop

I have been trying to get hold of the returns department since last week to return a faulty laptop I received, and now when I phone Cell C, They keep transferring me to a line where no one answers and when I asked them to get someone to phone me back regarding the issue they told me I should either go into a branch or just hold on as they can't get someone to phone me back - All I wanto to do is return a faulty laptop which I am paying for and get a new one instead - At this rate, I'll rather cancel the deal!!!!