credit card

I paid a settlement amount of R3640.00 on my Nedbank CC sumtym last year. Late last yr i started to rcv sms notification tht i must pay certain amount on my cc i bcame suprised bcos to my knowledge tht i paid them off n i ws told tht there's still -320-50 tht is still owing n the guy ws rude. Fair enough i paid 3 conservative months to pay off tht balance, nw i keep on getting sms's saying tht i shud pay min of R50 n the balance is 328 i find it strange at this s i dnt hv their cc anymore for almost 2yrs nw. I contacted nedbank cc n ws told by a lady tht they cnt trace the monies i paid etc. How cn i pay for something um nt using or having access to, being unemployed i tried to settle watever tht i cn bt this flipping bank is giving me a grief day in day out of my life.I HATE NEDBANK WITH A PASSION. I need sumone to sort this mess out s i dnt hv money to pay them um unemployed lost everything n stressed n nw they cum with this ****. Um aware tht i hv to pay bt for sumthing i dnt knw um definitely against it.