Sonkeigo (尊敬語) has one job: elevate the person *doing* the action — a client, teacher, or manager. The moment you put sonkeigo on your own action, the wiring is wrong. These examples come from live Business-style rewrites.
Wrong wiring: sonkeigo on your own action
Natural Japanese
私が言いました。
おっしゃる is sonkeigo for "say." Put it on 私が and you are accidentally elevating yourself. The proofread output drops it to plain 言いました (or humble 申しました for even more formality).
Proofread with Tadashii Kotoba (live API) — honorific misuse corrected.
Correct wiring: elevate the professor
Input
The professor said the deadline is next Friday.
Natural Japanese
教授が、締め切りは来週の金曜日であるとおっしゃっていました。
The professor is the subject → おっしゃっていました is correct. The direct translation had 言いました; Business style lifts it to sonkeigo because the professor is the elevated party.
Rewritten with Tadashii Kotoba — Business style, recipient: client (live API).
Two more sonkeigo verbs worth learning
Input
The section chief is here / in the office right now.
Natural Japanese
課長は現在、社内にいらっしゃいます。
いらっしゃいます is sonkeigo for いる (to be / to exist). When reporting a superior's whereabouts to a client, this is the natural choice.
Rewritten with Tadashii Kotoba — Business style, recipient: client (live API).
Input
Does the client already know about the new price?
Natural Japanese
クライアントは、新しい価格についてすでにご存知でしょうか。
ご存知 is sonkeigo for 知っている (to know). Used when asking whether a respected person is aware of something — standard in business.
Rewritten with Tadashii Kotoba — Business style, recipient: colleague (live API).
Quick reference: common sonkeigo verbs
Plain → Sonkeigo: いる → いらっしゃる ／ 言う → おっしゃる ／ する → なさる ／ 食べる・飲む → 召し上がる ／ 知っている → ご存知 ／ 来る → いらっしゃる／おいでになる ／ 見る → ご覧になる ／ もらう → お受け取りになる
All of these go on the other person's action — never on your own. For your own actions, switch to kenjōgo (humble forms): 言う → 申す, する → いたす, もらう → いただく.