I had a box of Kellogg's Raisin Bran with raisins that were (literally) as hard as little rocks. It was disgusting and inedible (not to mention I almost broke a tooth)... I wrote an email to Kellogg's via their website, and I told them that I normally like Kellogg's products and I was very disappointed. They sent me an apology and a coupon for a free box of cereal. I'm not going to tempt fate and buy Raisin Bran, tho. I think I'll go with a nice, safe box of Frosted Mini Wheats.
So I'd say, write to the company. It can't hurt - and blue plastic in bread crumbs is unacceptable! (I also find meatloaf unacceptable, but that is a whole other can of breadcrumbs). Of course, your other option is returning the breadcrumbs to the store where you bought them... Especially if you are a regular customer at the store!