settlement letter cellc

my cellc account was handed over to them 2017....and arranged to pay by term ..until last year November i requested the settlement amount of which I paid fully in november .I requested them to send me a settlement letter to prove I'm no nolonger owing ...until today I didn't receive a letter and that amount still appearing on ITC.. ...ive been calling and sending email no response . ..at first they referred me to cellc ....cellc referred me back to them ...im tired of this coz when they wanted my money they even called on awkward hours ....beware of this attorneys