I have just realized that this has also happened to me. Surfing on the web I realize I am not alone, many others like me and you. This is really frustrating since I have worked hard to earn these miles. I don't feel Aeroplan has informed me properly, a paper (mail) statement is what would have been effective with emphasis on the 12 month inactivity period. For some reason with the news I was made aware of the expiry date on each mile but not on the account inactivity period of 12 months which expires all the miles.
If anyone knows of a class action lawsuit please let me know.
This is a great complaint you have written and I feel the same. If would be nice if you could respond back with the result of your actions. Thanks