いずれにせよお客様にご心配をおかけし不快な思いをさせてしまったこと深くお詫び申し上げます。お客様の申し出通り全額返金にて対応させて頂きます。誠に申し訳ありませんが現在私のA口座にトラブルが発生しており、Aへ問い合わせたところ解消まで2~3日程度かかる見通しです。Bの仕組上A経由でしか返金出来ないためこのような状況になっています。問題が解消され次第、必ず直ちに全額返金を行うことをお約束致します。Aのトラブル解消の進展については随時お知らせします。返金手続完了後再度ご連絡します。
Anyway, I would like to humbly apologize for the inconvenience you have experienced. And I intend to handle your request for a full refund. I regret to inform you that there is a trouble with A account of mine; it is estimated that the issue will take a few days before it is solved. The system of B only allows me to refund youのvia A account. I promise you that I will fully reimburse you as soon as the issue has been solved.
I will let you know the progress of the trouble regarding the account. And I will contact you after the refund procedure has been completed.