Bad Service

My account was handed over to Hammond Pole Attorneys and I settled the outstanding amount by making an immediate payment on the 7th September 2020. I made an error when making payment and used the incorrect reference number which i was only made aware of weeks later when I called to enquire about the sms notifications I was sent stating my account was outstanding after I know to have settled the account. I've been sent from pillar to post, I'm getting sms's about an account I've settled which has since been sent to their accounts department for allocation. I've been waiting for the settlement letter. My credit report hasn't been updated to date. I'm really sick and tired of the service that Hammond provides for FNB. It's been too damn long.