United's Latest rip-off

Like most ex-Cons; the old Continental Airline frequent flyers, I am totally disappointed with the merger with United. Today I was privileged to discover the latest rip-off; another way to fleece customers and drive us to search for a viable alternative. I am booked to fly on tomorrow's flight at 7.30am. As I am within the normal 24 hour window, I decided to try to get a later flight, on which I know there are plenty seats. Looking online, the airline tried to charge me $236 for the change! Previously, as a Platinum, or 1K frequent flyer, I could make changes within 24 hours if there were seats available. Now United has cleverly said that there is no change fee, BUT they use a new fare basis, which is calculated as if I tried to reserve a one-way fair at this time. This results in a very expensive "L" class ticket. They then try to charge the difference between my original reasonably priced ticket and the expensive one-way ticket; a real rip-off. So, it means that I will not change and that I am angry with United.... again!