Don't go anywhere near FNB personal loans facilities, it's ******* service after that

FNB what have i done to deserve this treatment, what happened to your slogan of "How can we help you".Can someone explain to me what is going on with this loan i took in 2014 and was suppose to end in August 2018 but i was told that my account is in arrears because of the system generated instalment decrease(which even today i don't understand).i was told that i will have to pay it till December, but to my surprise there is a balance of -R9221.37 today regardless every month my account is being debited.Am i going to pay for this loan for the rest of my life? My credit record is bad now because of this. I am regretting the day i decided to take this loan, it was the biggest mistake of my life i have done.