Non-existent customer service!

I am being charged for a new contract on a phone that I returned to an MTN Direct store more than 5 weeks ago. This was a "sale" that led me to believe that I was entering a change to an existing contract, which was in fact a new contract. So now I have one phone (my existing one) and am paying for 2 contracts! It has been impossible to get any help via Customer service. The phones are constantly engaged, emails and face book messages go unanswered, or with a promise to get back to me that never materialises. The same goes for RewardsCo that handles the sales. I notice that any written communication is entirely avoided - leaves one wondering why??