Task: Determine the prevailing emotional tone of the tweet, categorizing it as either 'neutral or no emotion' or as one or more of the given emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that most accurately represent the tweeter's mental state.
Tweet: Incredibly shocked and disappointed with @united customer service. Really making me rethink flying with them in the future. #unhappy
This tweet contains emotions: 
anger, disgust, pessimism, sadness