extremely poor service

So get this,i grab a double deal at mtn and without my knowledge they charge me for both sim cards(because i didnt know that you are supposed to receive the second sim free)i go to a diffrent mtn branch and he tells me that sim deal has been like that since the very day mtn opened their doors for the first time,he then advised me to go back to the store that i bought it from.Why would you **** customers out of a quick buck like that?ive been making contact but my calls are constantly being placed on hold.