Service Message - Frontier has a "one-time benefit" to get back your miles.

My miles mysteriously disappeared today, 2/17/16. I do not have a screenshot of my expiration date but as of Dec 2015, I had 86,XXX miles. Today I logged on to check in for my flight tomorrow and saw my mileage balance was 0!

I called and learned that:
1) Miles expire every 6 months now if no activity is posted. I did not know this.
2) My 86,XXX miles mysteriously expired yesterday, 2/16/16.
3) I never received notification that miles were expiring but the rep said I should have received it and he apologized for not receiving it.
4) Activity consists of flying Frontier or using the Frontier MasterCard.

This was all interesting BUT I had used the Frontier MC to purchase a flight on 2/4/16 which was 12 days before the expiration date. My flight leaves tomorrow, 2/18/16. The rep offered that I should call Frontier MC (Barclay) to ask about their process of letting Frontier know I used the card. What??

So I had used my Frontier MC to keep my miles from expiring but Frontier didn't know I used the card so they took my 86,XXX miles.

The rep apologized several times, was sorry for my inconvenience, and alluded to the fact that they were working on fixing some issues like this.

He said after I fly Frontier tomorrow I am to call them back and as a "one time benefit" to me, they will credit back my miles. Oh thank you (said sarcastically since according to their rules, my miles should have never expired).

I will burn up these miles as soon as I can and doubtfully ever fly with them again. Too bad as in the early to mid-2000s they were my favorite airline and I flew them twice a week for work.