I presume you represent a corporate who had participated in a campus recruitment drive and you are responding to the college/ institute with your feedback on the experience. You could adapt the following to suit your specific requirements
Dear Sir /Madam or Mr. / Ms ______
Sub: Feedback on the campus recruitment drive held on ___ in which we had participated
Thank you very much for having invited us and for the (good/ excellent ) arrangements made for us when we conducted the campus drive at your institute on _____
In particular we would like to appreciate the warm reception accorded to us as also the facilities provided to us. The coordinator from your side Mr/ Ms ___ was most helpful in coordinating and facilitating the smooth flow of candidates during the interview process...
We would also suggest the following
Students waiting out side the interview rooms were loud and noisy and it would be better if the interview rooms are kept on the first floor and the students waiting their turn asked to wait on the ground floor....
Thank you once again for the arrangements made and we shall be shortly intimating about the outcome of the interview process. We hope to participate in this campus placements at your institute again next year.
The above is just a broad outline and you will have to suitably amend it to meet your exact requirements. I also suggest you run your final draft through someone who is strong in his/ her English language skills and Communication Skills so that the letter is a good representation of your corporate. It can also be the outline for future reference.
5th August 2016 From India, Mumbai