Poor Customer Service

I'm very frustrated and ****ed off by FNB in general after 11 years banking with them.I wanted to close my FNB Check card and revolving loan.I was owing them R49554.13 which a piad them this morning at 08:09 before going to bank to close both account as i cannot close one and leave cause they said they are linked.After i made the payment the balance was at R0.0,but when i got to branch and speaking to Makhumo she said i still owe R497.19 which i didnt understand where the amount come from cause on the system said R0.0.She insisted that this amount is the interest,how can i have a interest on a R0.0 amount.How do you calculate the interest of R0.0 balance?Due to desparation to get FNB on by life,i then pay the amonut of R497.19 as demanded.For my surprise ,they still didnt close the accounts.She made several call to other department for assistnace,but the final answer that i got is that the revolving loan cannot be closed and she need to send an email to someone to close the account tomorrow and also he cannot close the Check account cause they are linked.I left the branch frustrated and they told me to come tomorrow again to close the Check account.This left a bad taste in my mouth