Formal mail

Subject: Delay in our Friday appointment

Dear Ms. Jane Austen

I am terribly sorry, but due/bacause of to some problems concerning my plane tickets, I won't be able to arrive before 11 AM.

I regret to inform you.

If 11 o'clock does not wit you, feel free to set a different hour at your best convenience/that Works for you best.

I am very sorry for the inconveniences. A qick/Swift response would be highly appreciated in order to/so as to rearrange my agenda.