MTN Mokopane - Manager Refuses Refund or Product Replacement Of Faulty Router.

I bought a wireless sim router & starter pack on the 1st of October at MTN Mokopane and I was assisted by Nomsa. it worked perfectly for the first day, and the following evening, the device stopped functioning by not being able to power back on. I then returned the device since it is under manufacturer warranty. After TWO WEEKS of waiting without internet as a single mother, Nomsa called me on Sat 19 Oct and said "the router has arrived the previous day" and "that I can go fetch it", but when I arrived to pick it up - I had them test the device to see if it is working... To my disappointment, it was still in the same state I left it there two weeks ago... The device does not power on. I proceeded to insist on a refund since I am no longer satisfied with the kind of service that MTN South Africa is offering to SA citizens, but Nomsa refuses to do so. I also have no invoice, since a POD is all they gave me. How is there no proof of purchase when MTN is supposed to RICA the sim in-store? I am on system, and I demand my refund. If this is the kind of treatment that a company like MTN SA is upholding to the public, then I can only advise forclosure to this tiny shop situated in Mokopane, Pick n Pay Mall.