Horrible service ever

I had a personal loan with Standard bank for 33 months i was told by one of the consultants in the store my last payment will be end of August 2018, to my surprise another amount was debited from my account end of September 2018. I called the call centre and was not assisted at all the agent spoke over me as if i don't know what’s going on, i requested to speak to a TL i was told they not available. I asked to get a confirmation letter stating my account has been paid up this part was shocking "we don't provide customer with paid up / confirmation letters"

Can you please refer me to the department that can assist me, he kept on speaking about inception date. I'm really dissapointed,