MTN messed up won't fix it

I cannot believe how *********** mtn is! I bought a cellphone and tablet on a contract in December at mtn Highveld Mall. I was supposed to receive a Sim card for the tablet with airtime and data on. But they didn't give me a Sim card, I don't know how they did this but they loaded the airtime and data onto my husband's Sim card! And now his Sim card is *****ed. He can't buy voice minutes anymore and it costs a fortune to phone anyone. But do you think they can fix it? OF COURSE NOT. We have been there 4 times since they messed everything up, and they say they can't fix it. How can you not fix it? You messed it up, FIX IT! I emailed customer care with the whole story, and they told me to identify myself with my mtn pin. I don't know what my mtn pin is and i don't know where to get it, so rep**** and asked customer care and they said they cannot help me with anything unless I identify myself. What am I supposed to do?! I'm debating canceling all the contracts and moving my husband and I to another provider.