Why let the behavior of one employee (ok, maybe two) spoil your stay if you have been perfectly happy for the other 17nights.

I would be pissed too about being woken when I wanted to sleep. So send a nice mail to the GM that you don't appreciate this behavior and the subsequent responses. Probably you now will get a decent apology and get over it if it only happens once.

So no, not an acceptable response. But do you feel your reaction was that much better? You are calling her a liar (which she probably is) and want to get the DM to confirm your opinion. That's hardly going to happen... the best you could have hoped for is a statement that he has spoken with her and it's not going to happen again. But only time will tell....