FNB Loans

I'm not happy at all with my bank. I took a loan 2018 August and I took the 4 months payment plan that was suppose to end in December 2018 as per my agreement with the consultant that assisted me. I payed it up in December and even more than what I was suppose to pay. It was a hustle to get a refund for the money that was extra. I ended up getting it after a couple of weeks. To my suprise recently I'm getting the lawyers call telling me that I'm owing FNB for the loan that I took 2018 of which I did pay it up. But than now they telling me I'm owing R1900+ for that loan. I contacted the FNB Care department and I didn't get any help and the guy promised to get back to me which never happened. Now I'm busy getting unnecessary call from the lawyers saying I must pay them or they will take legal action. I will not pay the money that I payed before. To hell with that shame. I am seriously not pleased with their actions and I'm thinking of taking this matter to the ombudsman.