Poor After Sales Service

Had an issue with the tracker company (Matrix) where they took forever to install tracker on newly acquired vehicle. I cancelled them and obtained another service provider to assist me. Now the challenge is the amount I was invoiced for the vehicle included a portion of the tracker. I have requested Haval Kempton Park to credit me for that amount and to date they have not fixed it. I further contacted Haval South Africa and to date they have not resolved my query as well.