Car track complain

I installed the tracker on the 11th of March 2021,the tracker did not work, I called several times untill they send a technician for repairs on the 16th, the tracker was functioning, it stop functioning on the 20th, I called them, they promised to call me back, I called on the 22nd I got the same respond, I sent an email and no respond, I called on the 31st in the morning, they said they will call on the same day to make an appointment for the repairs, I did not receive any call, I called at night they promised to call me. I asked them to check my car on their system because on my cellphone it showed me the last location of the 20th and the car was used daily, they responded that the car was last seen on the 20th,what am I paying for if they can't locate my vehicle as promised of the contract. The tracker does not know and understand their new device and their technicians don't have proper knowledge about this new device. Im now worried if my car can get lost or hijack with my family I can not find or give them quick assistance, the tracker they installed they promised that it will detect when one get an accident but they don't even know where is my car, the stressing part is the slow assistance that I receive from them. Is there a way of canceling the contract because it does not serve the purpose I'm billed for