Lack of a response to a request to call me illustrates Tracker's lack of respect for it's clients

I have just sold my car which was fitted with a Tracker tracking device. I no longer need the account and want it to be closed. Tracker's App offers no way to do this and I sent a request over 24 hours ago for Tracker to contact me which has not been honoured with the courtesy of a response. I have not had time to contact them telephonically myself as I have just had a death in the family and am rushing around attending to many things but have had my phone with me and would have taken a call. They are so arrogantly self-assured of their own indispensability they clearly cannot imagine anyone ever wanting to cancel and are being obstructive in not providing for this on their app or website, and furthermore not responding to a request to be called.

Though I had no complaints about the service they have provided for the last four and a half years they have no respect for their clients if they can't bother to respond to a please call me message. All they want is to continue taking my money.