YOU SAID:

My sincere apologies for not having returned this yesterday as planned.

INTO JAPANESE

昨日、予定通りに返品できなかったことを心からおaびします。

BACK INTO ENGLISH

I sincerely apologize yesterday that we were unable to return the product as scheduled.

INTO JAPANESE

昨日、予定通り製品を返品できなかったことを心からおaび申し上げます。

BACK INTO ENGLISH

I sincerely apologize for failing to return the product as scheduled yesterday.

INTO JAPANESE

昨日予定通り製品を返品できなかったことを心からおaび申し上げます。

BACK INTO ENGLISH

We sincerely apologize for failing to return the product as scheduled yesterday.

INTO JAPANESE

昨日予定どおり製品を返品できなかったことを心よりおaび申し上げます。

BACK INTO ENGLISH

We sincerely apologize for failing to return the product as scheduled yesterday.