Computer Aided Waste!

My wife had heart surgery some years ago, and at her annual check up, a couple of weeks ago, her consultant suggested that she had an echo-cardiogram.
Last Friday she received a phone call from the local hospital saying that they had a cancellation and offered her an appointment for Monday morning, which she accepted. As arranged she attended and was obviously pleased to be told all was well.
Today (Wednesday 20th), she received a letter, first class mail, informing her that an appointment had been made for to attend the hospital on Monday 18th, etc.
Now I know it is only the cost of a first class stamp, an envelope and a page of computer print-out, by why waste even this amount?
But then I suppose, because of the ignorance of those who placed the contracts for the NHS IT system, it would now cost a fortune for a line of code to be added to the program to prevent this happening.