Stella was unhappy because she

M: Well, Sally? Why do you look unhappy?
W: Oh, Hill, I have just had a quarrel with Mr. Smith.
M: Mr. Smith! What on earth was it about?
W: Well, I have made three bad mistakes so far this week. Today I forgot to give him an important message, so he got very angry with me.
M: But I don’ t understand. You are usually very careful and never make mistakes.
W: I’ m just so tired. I don’ t know what I’ m doing.
M: Why? Have you been going to bed late these days?
W: No, I’ m usually in bed at about eleven. But I’ ve been woken up at about half
    past four every morning. And then I cannot go back to sleep again.
M: Why?
W: It’ s my new neighbor, the milkman next door. He gets up at half past four and he always turns the radio on loudly.
M: Ask him to turn it down then.
W: It’ s difficult. I don’ t know him yet.
M: If you don’ t want to see him, write him a letter.
W: Do you think it’ s a good idea?
M:Yes,I do. I’ ll help you write the letter.
W:OK. Let’ s try.