Sorry if this is not the right topic, but I couldn't find a more suitable one. I wanted to use my Miles & More miles to upgrade to business class on a United flight. I have a fare class Y ticket, and according to the table on the Miles & More website, such an upgrade should be possible for 35,000 miles. The flight is FRA–IAH. Unfortunately, I was told by a Miles & More representative that the upgrade is not possible because the airline (United) is refusing it. Has anyone experienced something like this? The chart clearly shows that an upgrade on United using miles is possible.