"Operation withdrawn within 20minutes of being..."

I have waited months for a date to have an operation on my ACL, after chasing for an appointment i was told likely hood is end of August. Then out of the blue I was called to be told there had been a cancellation and I was asked to come in (1 week) from receiving the call which although short timing is good news, and told the paper work is being sent first class to confirm this. I then called back within 30 minutes of receiving this call to confirm the details, and was told that in the 30 minutes from initial call an emergency had come up and my date (1 week) away had now been taken. I am aware emergency's take priority however no one had even called to make me aware and why offer someone a cancellation to than cancel that offer? Thankfully I called to check some details because I would be still none the wiser and had already booked this off with my work. Very poor communication, not a good sign of things to come, and back on the waiting list for another month at least so i am told.