Welcome to the forums, it would help if you can provide a little bit more information about your case so in the meantime my answers will be generic.
First be aware that to date Getty has not sued anyone in the states for just having one picture on a website, they will try to bully harass and scare you into paying.
I would contact the company were you got the template and see if they can provide you with the licensing information for the image in question. I don't know where you got the template from or how long ago but I remember a while back ago Template Monster got caught using Getty images without licenses and paid Getty retroactive licenses to make everything good for their users. I also know of a couple of cases where Getty tried to "double dip" by trying to collect from end-users on images that were settled previously by template monster.
Having said that if the company were you got your template cannot provide licensing information I would start by asking Getty for proof of claim meaning
1) To see verification that the image was filed with the U.S. Copyright Office
2) Verification that the copyright is either for the individual image or a group of images.
3) A copy of the signed contract, assignment or other documentation between Getty Imagesand the artist transferring copyright and giving you exclusive rights to the image as you havestated in your letter.
4) Sales history and records of this image and prices received for the image.
Getty will not provide any of this information to you as they most likely can't. You'll need to decide if you want ignore it which is not recommended by me, fight it on your own which is what I did, talk to Matthew using the Eli support call to get up to speed quickly and get a plan of action or retain Oscar using his defense letter program so you will not have to hear from Getty again.
Read the forums as there is pretty much everything you need to know to fight it yourself contained here and ask questions. Again welcome to the wonderful world of Getty extortion letters.
As far as your entrapment question I'm not really sure where you're going with that, could you please clarify?
I used a website template that I obtained online that has gotten me into this mess. How can I possibly confirm that Getty isn't using some off-shore presence to entrap me. I obviously can't prove it, but given their tactics it makes me wonder.