horrible service

I signed up with Cartrack end of November 2021 and i was told that if i want to downgrade i can at no cost, today i called as i wanted to downgrade i was told that i have to pay R350 for the device to be changed.I required to speak to the team leader and i was told that the team leader is on his way he will speak to me in 3 seconds they made me hold for more than 10 minutes, I want to cancel this contract not mentioning pathetic service that i got from them.