I submitted an order to them this morning that included a 20x24 crop of a particular image.... but oops, stupid me - I sent them the 2x3 ratio version of the image.
I got an email from them to warn me of the problem and just got off the phone with them. They switched it out with the new image ... no muss, no fuss.
And not only that, the images are already in pre-production... and I only submitted it this morning!
I've always been happy with their quality.. and now, I can brag about their service too.
No affiliation, just a happy customer.
http://www.canvasondemand.com