Letter to ask for an order

The other day, I bought some books on the internet. It was impossible for me pick them up. Yesterday I went to collect them but they were already at the post office. So I sent this email to the company:

"Good morning,

I am writing to you because I couldn't pick up my books at the post office. I went yesterday and they told me they had returned the package.
Could you please send the books to me again? Is this possible?

Kind regards,

Mariam

Letter to ask for an order
The other day, I bought some books online (on the internet is also fine). It was impossible for me to pick them up. (I went yesterday to take them buy they already were at the post office.) This line is total confusing (You can write ---I went to the post office to collect (to pick up) my mail but the post office has already retuned the order to the company) . So I sent this email to the company.

"Good morning, (it's better to write HI or HELLO because you don't know when the company would read the email)

I write to you because I couldn't pick up my books from the post office. I went yesterday and they told me they have returned the package.
Could you please send me the books again agaiin? Is it possible (it is not required in an email in such cases)

Kind regards,

Mariam