FNB Cant Give me answers

I have been banking with FNB for over 10yrs now and i never had serious issues with them until now, so I don't know if its because i have been their client for so long or what. 2 months ago I discovered that there's a loan account on my profile with an amount of 94000 which I don't know anything about, i have since been trying to get answers from FNB and I'm being sent from pillar to post, as a result till now I'm still waiting for answers, the sad part is that they promise to come back to me and they never did. So I don't know how FNB expects me to pay for something that they cant explain themselves and this account is busy accumulating interests on it, as a result to all of this my Credit Score is now bad because of it, so I don't know how else to handle this matter, so I really wonder what's happening here