Unauthorized debits by Tracker

After buying a new(2nd hand) vehicle I contacted a tracker dealer to install a system for me before I go on Holiday. Hopeless is not the word and after about a week of excuses and running out of time I contacted Netstar who installed a system the next day and advised Tracker that they do not need to send someone out any more. Tracker however went ahead and started debiting my Bank account without any signed agreement or voice recording. Following up with tracker Headoffice is absolutely futile with the staff member I am dealing now with for 3 months not even able or willing to put me in touch with a manager. The owner of the TRacker franchise, Dean, just pulled up his shoulder and did not even attempt to assist in any way. So it looks, in my experience, that once Tracker gets hold of your account details that they will debit your account with or without a signed or verbal/voice recording agreement and if you query it that you will be ignored.