Giving wrong information

Last month i retrieved a sms from American swizz i how them 79.00 i asked why and they said it an out standing i told them that i paid my account up to date in December i dont ow them anything cause i phoned in to get my total owed amount seeing i NEVER get statement from american swizz so after a few months they tell my i ow them money so i said ill pay the 79 rand but i am not going to pay interest on an amount i had no idea of and was wrongly informed about. they said its fine i only have to pay the R79 no they sms me my account is in the areas with R91.00 i phoned them now they giving me more stories the woman said she is going to speak to her supervisor i hanged on 45 min and then put down guess what no help what so ever. VERY VERY BAD CUSTOMER CARE. I will NEVER buy there again i rather go to sterns...