Can't close revolving credit loan.

I tried to call to close my revolving credit loan, and was transferred but no one answered. R30 airtime in the toilet for nothing. Why can't I just close the loan through the app? It's paid off, and I don't want to end up paying extra again for nothing. Last time I had this loan open, I paid it off and because it was not closed, I was debited twice and never got that money back. Close this loan and make it easier to manage this, it's absurd that we have to wait for someone else to assist with something so simple.