Yea the main reason for informing the manufacture is to inform them of the problem, not to bitch at them. Sorry if I came off like that. They may have had a bad production run that day, materials not mixed well, heat no hot enough, or something else.
At my work, when a customer calls with a complaint, most of the time we give them a credit. I have sometimes sent them a free 40 lb sample of our product to make up for the issue. I'd rather lose $200 of product on a free sample than to lose a customer that buys 2-3 truck loads a week. But that's my point of view.