Task: Assess the emotional content of the tweet and classify 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 best represent the tweeter's mental state.
Tweet: @Groupon_UK who do I contact about a shocking experience with Clear Sky Holidays booked through you guys?? #customerservicefail
This tweet contains emotions: 
anger, disgust, sadness