Service complaint

I have a credit card with FNB that I paid up in November 2019 in full and was told it was closed, but yet I still get charged every month for the account for a service I can't use coz it doesn't even show available credit so I'm basically paying for 2x Cheque accounts because that's how the use of my credit card works now. It also shows an active status on my app when it shouldn't and when I call to try sort out my problem then the consultant puts the call down on me, I don't know what more to do, so please if someone who can help me see's this please give me a call ***