I work at Menards and I can say that, YES, prices on shingles are out of control (petroleum product), supplies are spotty, if non-existent (manufacturer shortages). As far as poor service it is hard to comprehend some of the requests I receive in a day.
If you don't know what you want, how do I know what you want? At our store, if a "guest" has a problem we try to take care of it at store level (some of you folks request improbable resolutions like, "free" or unreasonable "compensation"). Unfortunately, manufacturers create products and warranty problems are the responsibility of the manufacturer. Menards can only act as an agent between you and the producer.
After all, this is a business and businesses have to make money to keep the doors open. I empathize with you who have had problems but I also see the people that expect the world for their, "I'm better than you" attitudes toward employees. I try to treat you like I want to be treated. As far as the the theft complaints, retail theft is a major factor that drives higher prices.
The people at Menards are just that, people, they make mistakes. If a mistake is made, I apologize.
But if you didn't get arrested I have to assume that the mistake was rectified.