I sent them an email yesterday, and they sent me this response:
Dear Value Meal 2,
Thank you for contacting us about your recent experience with United. I appreciate the opportunity to respond.
First of all, I apologize for your disappointment when you didn't get the seat you expected in Exit row. Furthermore, I want to assure you that your comfort and safety is our first priority each time you travel with us. Our flight crews receive extensive training, on a continual basis to handle any situation that may arise and while the event you experienced was certainly out of the ordinary. Most of our flight crew has been trained for with guidelines in such situations but I truly apologize for the inconvenience experienced by you. Nonetheless, I recognize this incident may have been stressful for you and regret any discomfort you may have experienced.
Value Meal 2, again I am sorry to learn about your recent travel experience. I'm sorry that you received a poor impression of United's ability to serve you. United staff has the training and ability to do a far better job than your comments indicate. Our employees should provide professional service. But, you report that some of my colleagues let you down, which resulted in your disappointment with our service. So I have forwarded your comments to the appropriate department for their review with the staff involved, which will work to ensure that the situation you describe does not happen again.
I trust you understand United considers all disciplinary measures between employee and manager to be confidential. Customer satisfaction is an integral part of our commitment to you. United's goal is to be the preferred airline of choice for every individual who travels. To achieve that objective we strive to provide all customers with the respect, courtesy, fairness and honesty they expect and deserve. Your comments clearly indicate that we failed to reach that objective.
It's important for you to know that the travel certificate was not meant to compensate you for your dissatisfaction. It was meant to serve as an expression of our appreciation for your business.
Value Meal 2, your business is important to us, so we hope this experience will not discourage you from traveling with us again. We'll do our utmost to make your future contacts with United satisfactory in every respect.
United Airlines Customer Relations
They also gave me $100 toward a domestic flight. Yay. You know, because I'm so going to be in the USA in the next year (I'm studying abroad in Ireland, hence the original trip to London). I'm not pleased. $100 is better than nothing, but...goddammit.