Car tracking devices

2 additional devices were installed in both my 2 vehicles, agent didn't not give us clarity about the devices e.g the billing, types of devices and even how they work. On the 15th December the bill arrives with additional amount and called them the other agent acknowledged the mistake the other agent did n promised to remove the 2 devices without a cost and to be refunded the money back. Made follow up on the 23 Dec they sent me settlement fee for them to deactivate the devices and when phoning back is only customer care who will refer u to cancellation department and u will hold for them for 30minutes to answer and n customer care will tell u to send them email as they cannot be reached. I tried calling them many times and no one answers.How do I pay for a devices that I don't understand how they work and no one explains..