poor service provision

i have been cancelling my tracker with matrix for more than six months now and am still not getting any assistance from the company. last year (2020) in September the battery on the device installed in my car died and have since been getting calls from them that they need to change the whole device, however they have been failing to do so and worse every time whenever they call me they promise to send me an agent to come and assist me. it has been more than six months that i have been sent from pillar to post without any assistance from them what is more frustrating they are still debiting money from my account on a monthly basis despite requesting them to cancel the debit as their device is no longer serving any purpose. several emails and calls have been sent to them (matrix beame) and they have made promises to cancel the account but it has always fallen on deaf ears. i need assistance with regards to this matter once and for all now.