Task: Analyze the tweet's emotional connotations and classify it as either 'neutral or no emotion' or as one or more of the specified emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best portray the tweeter's mental state.
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