Disappointed

I have a credit acc with u guys with a limit of R3000 and i have maxed the acc before and i never had to pay over R400 as a premium, i have a positive balance in my acc right now but suddenly i have to pay R959 how? what motivated this? are u guys trying to intentionally ruin my credit score on purpose? the contract i signed says i will only pay 5% of whatever i owe and i dont owe u guys that much please fix this and update your records as i work very hard to maintain a healthy credit and your card will not mess with that. Please dont add me to the list of the people i saw complaining on twitter about u