Write a letter of apology to a friend for having failed to keep an appointment

Dear Sunil,

I take this opportunity to apologies to you for not having been able to see you yesterday. I had promised to come to you at 4.00 p.m. and accompany you to Shri Ram Lai, our English teacher, in connection with tuition of your sister.

I am really sorry for this lapse on my part. But I am confident you will excuse me when you learn that such conduct of mine was unavoidable. At about 3.30 p.m. I received a telegram that my father was seriously ill. I had to rush home. In a hurry it did not strike me to phone you and cancel the appointment.

Father is much better now. After he makes a little more recovery, I shall come to you for the purpose specified above.

With best wishes,

Yours sincerely, X.Y.Z.