sim swap

I called in and spoke to Nhlanhla Khayile..what an *********** lady she is...just wanted to do a mere sim swap and to my suprise she is telling me that i should activate and load airtime...which i did...and then i called back again..and spoke to some indian woman and now telling me that they cant do a swim swap because i loaded airtime on that sim card....and She cant do a sim swap..asked the lady that do i have to make sure that i am left with no airtime in order for her to do that..and she is telling me no..have to buy the flipping sim card again...in the 1st place why did that woman tell me to buy airtime...Not at all happy...why would MTN put someone on a call centre if she does not know what she is doing...now I am stuck with a sim card that has 12rand airtime because of some stupid person...