Mtn south africa is a ****

The ****ming happening in mafikeng mall mtn is way out of line now, I bought a laptop from mtn, they gave me a broken laptop claiming is new the same week the laptop came is started to give me a problem of freezing and showing the blue and black screen then I took it back, they booked it in for rapair, what are they repairing I don't know because the laptop is "new" after a month it came but still the problem continued I took it back again 3 times even today I'm still in the dark but want me to pay every month, how? Please go to cell c or vodacom for the best service mtn is very bad.