Please let me hear your story once again.

Could you please send me a letter?

I'm sorry to ask you again and again, but could you explain it one more time?

I'm sincerely sorry, I was late because of my mistake.

I'm sorry, but we are fully booked and cannot accommodate you.

I apologize, but I will have to hang up the phone.

He gave me a detailed explanation of the problem.

He explained the problem.

Please read this instruction manual carefully before using the product.

Please read this instruction manual carefully before using the product.