Task: Identify the primary emotion conveyed in the tweet and assign it to either 'neutral or no emotion' or one or more of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best capture 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