Russells
Account outstanding after settlement was paid

I requested a settlement letter from local branch. A few days later it was paid., and i considered this matter closed.
Only to get an account from Russells a few months later stating that i owe about R1000 - which is now R1200.
After numerous conversations with staff, and sending an email to the relevant departments, still nothing.
Today i got a phone call from someone at the local branch called Esther, demanding i pay the R1200, and having a bad attitude about it.
And she is now saying i have to pay it, i don't have a choice. And stating that i promised that i will pay the outstanding amount. It doesn't make sense to me, because why would i pay the settlement and still pay another amount???
i have heard rumors of a few people with similar and other complaints with this company. You cant go with rumors, so i bought what i needed from them anyway. Now having this experience, i can see where these rumors come from. Something needs to be done. Can you please help me with this.