Cell C and MBD

I had a very bad experience wirh Cell C who handed me over for money they claimed I owe them. I was issued a *****ulant contract. After I wrote a review on Helopete, it took a while for them to issued a paid up letter on 21 December 2023. MBD is still phoning me every day about an outstanding amount I owe Cell C.. I'm very upset because I now have a bad credit record and MBD do nothing about it. What more can I do to get MBD off my back, and will my name be cleared. Cell C and MBD my greatest nigtmare.