Dear khun Thanida,
For several visits to Shell in Bangalore, India in the next few months for the CFP project, I have to apply for a multiple entry business visa for India. One of the (many) requirements is a certificate letter that I work with PTTES, along the same lines as you made for the China visit. I have drafted the text in attached word document. Hope you can prepare the letter at short notice, scan it and email to me.
Thanks for your help !