Flying Delta from Portland, Oregon to Valencia, Spain and leave in 3 days. I am extremely unsatisfied with the poor customer service received from Delta so far. This is an expensive ticket and I've handled everything correctly as we are seasoned travelers and I always make all of the the travel arrangements for our family. In fact, travel and tourism is exactly what my major was in college (don't ask me how many years ago that was!). My daughter and I are traveling together to spend time with our exchange student who came and lived with us this fall in Oregon to attend school at my daughter's Christian high school. She became one of the family and is an amazing girl who we've missed dearly since she returned home. My tickets were purchased through Orbitz in late fall and then Delta took the tickets over when there was a flight change for our layover in Paris. Delta contacted me to work with me in scheduling a different flight and at that time I worked with the customer service rep. from Delta to lock in all of my seats as I always do when traveling. Today I contacted Delta to confirm gates, times, flight numbers etc. and to my shock and great dismay I found that the representative who originally helped me in finding all of the seats together had not locked in my daughter's seat as she was supposed to. Of course it's on the 10 hour flight from Seattle to Paris! I was very polite in explaining that we need those seats together and that clearly I had already worked with someone to get all of the other seating arrangements handled so this was an obvious error on there part and could they please help me remedy this? The attitude was super disappointing as first the customer service rep. then her supervisor both told me they couldn't help me and I needed to try my luck asking at the gate, no guarantees! I want to make it clear that I was more than nice and polite when explaining this and asking for help. I don't believe it is right to become angry or rude with a companies representative over the phone when they are not directly responsible for an error. I was more than respectful and kind and in spite of this they completely refused to help me on any level. Only a child 5 or under has the right to sit beside a parent I was told. I'm sorry but I do not want my 15 year old daughter to be seated by a complete stranger for a 10 hour flight. Especially when I was given a seat assignment to begin with and since a representative forgot to hit the "enter" key or click the right field now I'm stuck in this situation. We have never had a problem with seating assignments before now and I'm sure the fact that I always go out of my way to book early and handle this first thing helps. This was their error and needs to be remedied. When I asked for a more senior manager to speak to I was told that I could lodge a complaint over Delta's website and would be contacted within 7-10 days... I cannot believe that the supervisor even suggested this to me knowing I'm traveling in 3 days and the flight is on my first date of travel. Not sure where to turn next and have no other contact information for Delta managment.