"Extensive appointment waiting times"

I had a pet scan to check for a possible cancer recurrence late June 2021 with a follow-up phone call appointment for initial results a little over a week later that appeared to have no major cause of concern but the Dr said they also wanted a face-to-face appointment follow up to discuss the results in full and to expect an appointment in the following weeks to a month.

I had not received anything by early September so I called up to see if I had an appointment scheduled yet and was told not yet. I finally received a letter mid-September for this month. 2 days before my appointment I received a text message to say it was cancelled.

I lost a day's pay off work for that. Not to mention the uncertainty of knowing that the Dr is insisting on a face-to-face appointment to discuss my results in full. I know it's likely nothing to be worried about but this hospital has previously contributed to significant mental trauma and severe trust issues within any medical setting due to apparently forgotten malignant biopsies and the constant extensive waiting is having an impact on my life. 

Why haven't I received a new appointment date? And why is it taking so long? Going by the date of my last scan and the fact the appointment letters, as I understand it, are sent a month before the appointment, by the time I receive an actual appointment I will be due for my next scheduled 6 monthly checkups.