Cannot even do a new sim only contract correctly

I tried to get two contracts on Sunday, for sim only for family. Went to the Shelley Beach mall to that MTN. Small little sim only contracts. All started well, only need one new SIM card as the other one I just wanted to add. Then the problems started. With security question.....everyone I answered correctly, but no, the system just did not want to accept any. Then the guy just told me, sorry I am blocked, but here is the new SIM card , they will let me know. So far I've heard nothing, I phoned MTN and they don't even have the order number. Then they wanted to do the upgrade, but only if they can ship new SIM cards, I told them that I already have the SIM cards, but nope they do not accept that, its cool, I'll go to Vodacom, am sure they would want the business