Avis forced app on me

I booked a car online with Avis to collect at George airport 24 July 2019. This was the first time with Avis that no paperwork was involved. Nothing was explained in terms of extras, no where to initial. I took out comprehensive insurance. My credit card and drivers license were verified, I was then told to sign with my finger on a screen. The consultant then asked me for my phone (I erred here to not ask why) He installed the Avis safe drive app, it was NOT verbally or any other way explained there was a charge of just over R139 for this app. He handed me a little device to put in the car. As I left the airport my cell phone beeped and beeped giving me a score out of 100 on how I was driving. By the 2nd day I deleted the app which was also draining my battery, it was highly irritating. I returned the car in good order on 1 Aug 2019 and received the statement by email a few days later, I then noticed the extra charge and immediately contacted customer services by mail (which I have all copies of) The refuse to assist me as I signed, I explained the story 3 times and am awaiting their response. I want a refund. This is a matter of principle, the agent should have explained there would be a charge and explained the app, I most certainly would have refused it as I think it is an invasion of my privacy and a jolly nuisance. I was comprehensively insured! I demand a refund