Also you might consider keeping the miles alive by, I don't know, using them to fly? If you had 150K at one point, depending on how that was spread among programs, you likely had opportunities to use them for a fair amount of free travel or upgrades.

There are different philosophies, of course, with some folks preferring to save up a large amount of time and others redeeming them frequently. Maybe you were saving them up and that's fine, too. But regardless, it's certainly not that difficult to keep miles alive. Nor is it that hard to keep track of your balances - there are services that will link and track them for you if you don't wish to do so manually. If nothing else put a red circle on your calendar with a note to check balances once a year.

I don't feel an expiration period of 18 months or more is out of line. And in most cases, the expiration terms are set forth in the program guidelines at the time you sign up so it's difficult to accuse the airlines of anything untoward.