"One didn't work why would she think the other would??"

Because the cc company will accept it in a dispute.

And that's the issue on the table at this point.
Excuse me. That's the POTENTIAL issue on the table.
A cancellation # is what the cc company will need.
Not a letter from doctor/lawyer/mommy/hotel.

Well as I posted on May 25th, we did receive the cancellation over the phone. When we received our CC statement the hotel had charged us for the room. I contacted the hotel and they informed me that the cancellation number I had been given was not in their computer system so there was nothing they could do about the room charge. As I previously stated our CC Co. did reverse the charge but due to that experience I can relate to a person wanting an email with the cancellation number.

Why would the credit card company just accept a cancellation number? Couldn't anyone just make up a cancellation number? It would have to be a cancellation number recognized by the hotel chain. So, this faulty hotel system could easily mess-up again and say that there is no such cancellation number in their faulty reservation system, right? I say, good move getting the manager to elaborate.

And I would like to know what your room rate was for the night. I'll bet $99 guests all got booted by this mysterious glitch while the $149 guests are all still reserved! Did the hotel ever say that they would re-instate your reservation or contact you as soon as they had a cancellation?

some hotels and sites charge a $25 penalty if YOU cancel or change the reservation. A cancellation number does not provide that information. Getting a letter in writing does.

Businesses can and do make mistakes.... those that try to rectify their mistakes are the ones that keep my loyalty. And, notifying me of their mistakes is NOT rectifying it. It is merely dumping an "oh sorry" in my lap.