who gave u authority to deduct on my account when

My account is paid up I have spoken to an agent and asked what does Settlement amount mean the answer was this is not a loan where u request for a settlement amount than the account is settled according to my knowledge when someone request for a settlement amount u calculates whatever is outstanding on the account n give a figure once the pmt reflects u request for a paid up letter n I don't understand how they changed my number to prepaid while I'm still owing than he ****ed me off n hung up while speaking the next thing was an sms we will attend to your query shortly guess what deduction was following n now I wonder where is my paid up letter bcs tommorrow I'm taking this matter further cell c doesn,'t follow the national credit act but I will teach u guys not to play with customers with a thought they don't know consumer rights,on the contract I signed with u it not stating that there are cancellation fees that are being charged secondly if the agent I spoke to in December didn't add the Dec usage it not my problem as a Customer that u gave a wrong settlement amount I paid accordingly n threatening with ncb doesn solve a problem I will report to ncr n clientele legal is behind u