No phone answering.....

I dont know how this is even possible?? I have started calling MTN stores at Eikestad mall and move along almost every mall right up to waterfront Cape Town. Not 1 of them has answered their phone. How does this happen?? If the shop is open... aren't you supposed to answer the phone when it rings? I mean... this is n mobile networks shop and international company. But unreachable on mobile.... Even a answering machine would have made me feel better.