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: @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