We regret to inform you that .....
We are sorry to tell you that...
We are sorry to say that...
Thanks a lot for telling me about this.
Thanks for bringing this to my attention.
I appreciate you bringing this matter to my attention.
I am very unhappy about the service they gave me.
I am extremely dissatisfied with the service I received.
I'm not happy with the service I recieved.
I'm writing to give you some details regarding....
I want to tell you about...
I'd like to tell you about...
I have a ton of experience in this area.
I have a considerable amount of experience in this area.
I have a lot of experience in this area.
I can't come to your party tomorrow.
I won't be able to come to your party tomorrow.
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How are you?
How's it going?