Poor service

Good day guys, In November 2017 I signed up with cartrack, they came to my house and fitted the tracking device, the technician informed me that someone will come to test if the device was fitted correctly, however no one came. In Feb 2018 I started having issues with the device, receiving endless calls from their call centre and we agreed that they will come and replace the device, they never came until I decided to cancel the service and reverse debit orders because i was paying for the service i was not receiving. I told them that i can only continue with payment provided they credit me for the months i paid without service but they didnt