Task: Classify the mental state of the tweeter based on the tweet, determining if it is 'neutral or no emotion' or characterized by any of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust).
Tweet: @SalterUK second pair of scales I have bought that have stopped working after battery change. Is this an issue you are aware of?  #unhappy
This tweet contains emotions: 
anger, pessimism, sadness