Poor service, and being ignored by Imperial Nissan Menlyn

Good day, I recently bought a car with Imperial Nissan in Menlyn on the 23rd of March 2018, the terms of sale were quickly rushed and it was closing time, all they were interested on was the installment amount. i had to dig for myself if this deal include a ballon payment, everything was explained in a sense that this car comes with Smash and grab, scratch and dent warranty and a car tracker and to my surprise i find myself signing a lot more contracts and i took the car and on the 27th of March i wrote back cancelling the car track and as was not fitted as yet, and then few days later the car track company called me to initiate the installation and i told them i've cancelled already. I made a follow up with the company more than five times now and i even copied their principal dealership manger and till today, know one is responding or writing back to me. I asked if that they must pay back to my MFC account the monies that were supposed to be transferred to the car track company. I have also written to the sales person and the finance manager including the Pricipal dealership, but no response or refund of the tracker amount financed by the bank.