Jack,
I hate to say this since it seems to offend you but the credit card company has not asked anything unreasonable of you. That doesn't mean that it is easy or not onerous for you to fulfill, simply a valid requirement on their part. It seems silly to say but just because you know that this particular airline has folded does not in anyway mean that it is common or universal knowledge or of general concern to the vast majority of the population. It is of eminent concern to you as you are out of pocket but of limited interest to other parties. Airlines actually fold on a pretty frequent basis. It is rarely news unless they are substantial holdings.
It is up to you to prove that your claim is valid not the credit card company. As already stated, the way to go about this is to approach KPMG requesting they advise you of what return you can expect (probably nil but experience isn the same as hard fact) and then send this to your credit card company to re-imburse you. What is evident is that you don't want to hear this because it means that you have to actively do something. You want someone to agree with you that your credit card company should coming running over and pick up all the pieces for you. They won't, you need to pick yourself up first.
So-crates.