Have had flights booked with UA for a trip to Croatia, one flight is with LH from FRA to ZAG. Have had minor sched changes over the past 3/4 months and other slight problems which have all been corrected by UA. The last change was about a week ago, apparently UA did not send the re-issued ticket to LH and LH cancelled the flight. Luckly I check my PNR's daily or I would not have know this until I arrived in FRA for the connecting flight. Called the 1k desk and was assisted by one of the nicest agents I have ever dealt with, she was friendly, concerned about the cancelled flight and assured me that the problem would be resolved. Was on hold with her for about 45 minutes while it was straightened out, also had to be re-booked in a higher class of service to guarantee that I would get my miles for it. I have just booked my first flight for 2013, this will take place in Jan. I found flights from SEA to IAD to FRA and then from OPT back to SEA which would allow me immediately to use to 2GPU's. Booked the flights but then when I went to choose the seats, I could not do it. Called the 1K desk and again a most helpful agent. Pleasant and helpful, she said she would have to do it manually, she was a pre UA agent and she said it would take a little while as she was still learning SHARES, however there was an agent that was helping out who was from CO and could help take care of the problem. About 25 minutes later, all seats were assigned. I had no problem waiting on the phone, the two agents I interacted with were great. I am very happy with the outcome. I think that for the time being, all of us should present a positive attitude until the problems are worked out with the new UA, we would better serve ourselves and most of all the people that are trying to serve us.