Disgusting bank

I am utterly disapointed in fnb as they have placed myself in a very difficult financial situation as i settled my fnb personal loan in June 2022 in full however they somehow reversed the amount without my knowledge and now i owe them exactly what i settled. I have contacted online chat so many times and no one can help. I need to know why the money was reversed and why loan was not settled. I want this matter rectified asap as my credit ability is ruined because of this stupid loan. Fnb is a *****!