Store Manager Screaming and Shouting at customer - Tiger Wheel n Tyre Bruma

I was told by Discovery insure to go to the Tiger Wheel n Tyre in Bruma to remove the "dud' SVR unit tracker that was installed in my car by them. This store does not have stock of replacement units as I had to get their Woodmead branch to install a new one. The Bruma branch refused to remove the dud unit that they installed into my vehicle. I spoke to their Manager Pieter who was rude and aggressive to me in front of customers and staff. He refused to talk to me and told me that he was having a good day and that he did not need me to bring my issues to him. I was utterly embarassed and also helpless. This guy is clearly a bully because no one came to help me or resolve anything for a customer such as myself. I was left standing outside the store. Discovery Insure put me into this predicament since I am a Discovery customer and I am annoyed for them to put me in vulnerable position. Discovery needs to demand more from the partners to satisfy customers. Despite the fact that this was my vehicle and that I had every right to ask them to remove this faulty unit in my vehicle which was installed without my permission to TWnT, Pieter was shouting at me instructions that I needed to tell discovery to deactivate this unit and that they would not know where they (TWnT) put this "dud" unit in my vehicle. This was clearly too much hassle for TWnT to remove. I will not go to this store again due to the store Manager's (Pieter) aggressiveness. Is this what the TWnT brand is about. Disgusted! Discovery needs to take accountability for this horribleness with TWnT; as I should not be resolving TWnT incompetence. If this unit is causing electronic issues in my vehicle, how would I get removed? (because TwnT has no paperwork for the installation). Someone needs to be taken to task for this gross negligence on vehicles.