Bought a Kodak printer a few months ago and, after just a few pages, the second lot of ink that I'd bought wouldn't print out at all.
Emailed Kodak who suggested various things to do but the only thing that worked was putting a new ink cartridge in. They cost around £14 each so when they emailed to ask if problem was fixed I said the above.
Received an email today checking my address to send me a free ink cartrtidge!
I'm really surprised at this great service, but I suppose it is how it should be in an ideal world. I just didn't think I lived in one!