How do I properly tell someone to proceed with a transaction in an email?

Question

Today, I received the following email after an online purchase:

この度はご注文いただき誠にありがとうございます。

頂きましたご注文の発送方法について、EMS(国際スピード郵便)による配送となりますので、 送料が1,500円かかります。

よろしければ、クレジット決済金額の変更をし、商品を発送いたします。 お手数をおかけいたしますが、ご返信をお願いいたします。

I am having a great deal of trouble finding common phrases to respond to in e-commerce related conversations over email.

What is the proper way to give the sender permission to proceed?

Every phrase that I would like to use in English seems to have a dual meaning which does not work in Japanese (e.g. please go ahead), or produces very few google results for the phrase which suggests to me that no-one speaks in that manner.

I spent several hours trying to find a way of saying, "Is it possible to use registered shipping instead? If not, please proceed."

My best attempt is something along the lines of

「書留郵便ができるでしょうか？如何とも決済金額の変更して, 追加送料を払ってください。」

but I really have no idea how accurate my vocabulary is. Considering some of these words yield little to no search results when I google them, I suspect this is wrong.

Where can I even find examples of conversations of this nature to learn what to say?

Answer 1

Is it possible to use registered shipping instead? If not, please proceed.
EMS(国際スピード郵便)ではなく、国際書留で送っていただくことはできませんか。もし無理なようでしたら、そのまま(1,500円のEMSで)手続きを進めてくださって結構です。

Answer 2

Speedy EMS (?) does appear have a registered service:

https://www.post.japanpost.jp/whats_new/2011/0307_01.html

So you could just ask to be told how much it would cost for registered mail. (You never know the cost provided may already be registered)

本注文ですが、国際スピード郵便(EMS)と国際書留サービスで郵送していただきたいですが、いかがでしょうか？ もし可能でしたら、その送料を教えてください。

どうぞよろしくお願い致します

Answer 3

If you just want to say proceed.

表題の件ですが、承知いたしました。問題ありません。

どうぞよろしくお願い致します