So Sorry for your loss
How is your other kitten?
ive heard this before- on here and from vets. Sadly its not well known in the general public where it is felt that if its available in supermarkets it must be safe. the rules that govern what testing is required for animal products are very lax compared to what is required for human products.
i would write to everyone you can- local and national papers, cat clubs and magazines, supermarkets and retailers- especially the one you purchased from. i know many have done this before but the more that do, the more likely it is that they will act. Bob martin seem to be aware but while they can sell their products they continue to.