Fnb loan

I took up a loan with Fnb in 2016 with repayment of over 5 years and my monthly payment of R3100 4 years later my amount due is still the same. I acknowledge that I missed about 3 payment and has an arrangement to pay 1000 extra to cover the areas amount. When I check on my app in the couple of months back they were deducting an extra R200 without my approval and my interest is over R2000 each month. The loan I took was R70000 and to date I’m still owing Fnb over R67000