Email companies to get coupons

I have purchased several products and have been very unhappy with quality or taste. I started to email the company that makes that product. Here's a perfect example:

My quesadillas Farm Rich product purchased yesterday was not what it should have been. One bag was just basically bread and cheese with no meat. I emailed them and told them about my experience with their product, I did save package so could enter information off of it. They returned an email within 2 hours to apologize and thank me for my comments, also to let me know that replacement coupons for free products would be mailed immediately to me.

Purchased Betty Crocker cake mixes for sons birthday. Upon trying to ice them as you would any other cake, they crumbled to pieces. I email General Mills over this and let them know what happened and the circumstances and how unhappy I was with their product. In response received 4 coupons that were $6.00 each of General Mills products. I then used those to buy 4 boxes of cereal for my family. Which also had movie e-cash codes on them. So not only did I get four free boxes of cereal but also two free movie tickets.

So if you are unhappy with a product let the company know, or if you are happy let them know. I have had several companies send me coupons just for complimenting their products.