Cell C Contract fully paid buf no paid up letter has been sent to me

Hi I made a full payment of my contracted items on the 23rd December 2025

I tried calling Cell C numerous times the collection departments phone isn't working

I still find myself black listed thou I have made payment

I had to beg and beg for assistance i was only sent a reference number which the agents can't send me the paid up letter

I'm really disappointed

Kindly advise which steps should I follow inches regard