用英文應該點寫

如果我想寫有個員工佢操守有問題，未經許可偷取公司客戶個人資料然後聯絡客戶到自己開設的公司(搶客)，
One of our employees has a conduct problem, who took the clients' data from this company without permission than contact them by the name of his own established company.

One of our employee is misconduct, he steal our client's infomration and contact them in the name of his own company without our prior authorization.

I assume you are writing this to your boss, otherwise the wordings may be different.
It has come to my notice that one of our staff members has violated our company's ethical conduct of stealing information of customers in our records. The information is then be used by his privately-owned company for soliciting a business out from us.