Extremely Bad service

I have paid off my FNB loan that was handed over to the ARA Group on the 6th of February 2021 but I am having problems now with the account being closed as the other collection company called me and told me I am still owing FNB where as I had confirmed with ARA if they received the payment and they confirmed that was on the 8th of February, I even sent the Proof of Payment to Their email address that they provided. On the 26th of March 2021 a company called Ismail and Dahya Attorneys called and told me I still owe FNB the same amount of money I paid to ARA group, when I call ARA group they telling me the account was closed with them and they sending me from pillar to post. I work 8 to 5 and I have to keep on calling them during my lunch time with no assistance, I am fed up now FNB please fix this as I have paid you fully. I did not have a problem with Anders Inc. Attorneys which I paid after the ARA Group, I received the paid up letter and everything is updated on credit bureau. I am really frustrated now with the calls that keep on coming in telling me I owe FNB knowing very well that I settled their debt