AngryDesi,
I bet you are madder at you than at him for putting yourself in this situation. I have been in situations like that myself. You oughta know that these INS officers maybe do not make as much as you do and that probably rankles. There maybe a few that harbor ill will maybe even hatred towards immigrants. As long as you are in the right they will be courtesy personified. Do you remember the mocking, nay insulting comments faced by the H1B folks who were arrested by INS agents in San Antonio a few years back. Those are the situations when all pentup negative feelings come to the surface.
I know, your issue now is you think you have been treated shabbily and humiliated and you need redressal. You have 2 options as already pointed out by rsrgc and goldengate. Lets examine each option.
1) You let it slide.
Wait for a couple of days and you may realize that your anger has dissipated. You may realize that it is not worthwhile generating negative emotions in yourself, family and friends for the actions of one person. Moreover, this person does not mean anything at all and will never have a bearing on your life. You may never come into contact with person again. So, is it worth losing your peace of mind and happiness over such an insignificant person? Like rsrgc pointed out, it takes all kinds to make a world. We take care to not to get ourselves into situations where we meet angry, bigoted and negative people. But, sometimes it becomes unavoidable. You just put it behind you and move on. Think forward to a time 5 years in the future. At that time would this incident have had any bearing on the course of your life? The answer you would come up with is No! But, I can assure you that you will not forget. Unfortunately bad incidents have a tendency to take up indelible spots in our memory. Next time do not give anybody else a chance to treat you like that.
2) You draft a letter and complain to his Supervisor.
This approach is fraught with complications. First do you remember his Name, Id number etc by which you can isolate him out of the dozens of folks who work there? Even if you did who would you address your letter to? Even if you addressed it to the right person what are the chances it will reach him/her? Lets say your letter reached the correct Supervisor. I am sure S/he is bound to bring this up with the errant employee. This is what supervisors do. Now, is this errant employee going to agree with what you said? No! He will defend himself with the perfectly credible argument that you were pissed off at being turned away and are trying to get back at the officer. It becomes a case of He said, She said. Nothing really will come of it. Such situations happen all the time in Customer Service situations. The supervisor will eventually have to dismiss it especially if this is the first complaint of its nature against that officer.
3) A third option is to get a lawyer involved and file a formal complaint. That involves a lot of money, energy and time. You will be bled dry fighting a corporation which INS really is. Its not like you can prove anything conclusively. The most you can get out of option 2 or 3 is an apology. I really don\'t think you are going to get even that.
I understand your outrage and anger and emphatize with you. But, I suggest that you let this slide and move on. Your aims and goals are far bigger and much more important than getting involved further in this mess. It may feel cowardly to not do anything and lump it but that is the practical and prudent thing to do. Hope you get your approval soon and move on.