Not fixing problems of phone that is still under contract

I wish I could give minus twenty stars to this place. My phone, which is still under contract with MTN (last time I'll have a contract with them, by the way) stopped recognising my SIM card. I handed it in for repairs and was told, after two weeks, that they can only fix the problem if I also have a scratch (not crack) on the screen fixed, which will cost me R 1270. This is absolute bull****. How can you sell people stuff that doesn't work , and then try to make additional unsolicited repairs a pre-condition for fixing the problem with the item you sold? Kind of like I go to Pick and Pay, buy sour milk and when I go back to return it am told that I can only do so if I also buy a kilo of beef fillets. Totally ridiculous.