Bad service

I bought a decoder from.dstv two years back few months after guarantee ends their ***ong decoder stop working when I go to their service center I was advised to bring the old one n replace it for R698 or buy a new one because I was uninsured I opted for the replacement then and paid 698 to my surprise their new decoder is not giving me sound or picture when I call the call center spoke to some guy who ddnt even tell me his name and while we busy on the call which took long without a solution before I could ran of airtime I asked him to call me back as am running out he tells me he can't call me I asked him so your living me with solution he dsnt respond now am stuck with their ghost decoder that is not working my money is gone