"Appointment cancelled, but the cancellation letter arrived after the date of my appointment"

I had an appointment scheduled for mid June with a doctor. When I arrived at the hospital I was told that the appointment had been cancelled and that a letter had been sent out a few days before to inform me. I received the letter the day after my appointment!

I had to return from visiting my daughter hours away to make the appointment, which cost me £40 as a return trip in fuel which I would not have had to make if I had received the letter before the appointments rather than after it.

I find it hard to believe that the letter was dated for a few days before my appointment but postmarked for the day of my appointment, therefore stating that the letter had been posted on the day of my appointment.