This morning I happened to check my United MileagePlus account for no apparent reason and there was a big surprise waiting for me. A hacker had gotten into my account and used up almost all of my miles to make a hotel reservation. I was able to have the reservation cancelled and have the miles posted back into my account. But it was a close call as the hotel reservation had been made today for a stay starting in two days. If I had found out about it after the hotel stay was over, I probably would have been out of all my miles in that account. The phone trail was as follows: Call to customer service for MileageMiles - advised to send an email to the corporate security team at firstname.lastname@example.org. Since the miles had been redeemed for a hotel stay, I was also given the no. for the hotel award dept. The Hotel Award Dept. was unable to help me as the reservation was not in my name and I did not have the the hotel reservation no. The agent advised me to send an email to the security team and also gave me the web support team's no. to change my pin on the account. The web support agent guided me in locating the hotel reservation in my online account. The situation being urgent, she cancelled the hotel reservation and the miles automatically got re-posted into my account. What a relief! The security team's automated response was that somebody will get back to me in 7-10 business days. Although they are closed over the weekend, the email was replied to within a short time and I was asked to change my pin and to reply back after the pin change to get the hotel reservation cancelled and the miles re-posted. As it happened, the web support person's effort was faster because of phone contact instead of the back and forth email contact with security and everything turned out fine. Just a heads up for others who might get their accounts compromised and miles stolen. Thank you United for your help.