Who can I speak to for assistance PLEASE?

I have a contract (tablet) with MTN. I am sooooo disgusted with the sevice or actually the lack thereof. The tablet did not connect to the network. I phoned the store at wonderpark 4 times. The first 3 times I left a message on the answering machine and days later I phoned again and to my surprise a man answered the phone. He was going to call me back as he was busy and I awaited the call until last week. After no call back I got in my car and went to the store. Spoke to them and they advised to contact their a ccounts department as there is something wrong with my account. Spoke to accounts and found that the debit order was not deducted from my bank account and ut is with their legal department. Told them that no one contacted me regarding any arrears and that I would like to resolve the issue. Thei promised to call me back. Went to the store three days later as I have not received the promised call. They phoned again to the department and I explained that I need assistance. I was promised to receive a call within 24 hours. Today, 4 days later and no call from them, I phoned the customer care deparment and explained the situation. I was told that their systems are down and they will call me back soon. It is now another 8 hours kater and no response. Who can I call to assist?