如何寫英文侍奉證明書？

To whom it may concern
This is to certify that Mr. Chan Tai Man is serving in our church, name of the church, as usher (接待) for more than four years. He is willing to serve and report his duty on time. He is also very polite and is willing to help. As his superior for a long time, I highly recommend him to you. If you have any question and inquiry about him, please feel free to give me a call at 9876 5432.
Your sincerely,

LEE Shan-Shan, Deacon (執事) of the (name of the church)
Date:

不是侍奉,而是事奉.教會領袖無可能會寫錯事奉二字.