I use Fineartamerica/Pixels to print and ship my photos. Their return policy is very simple:
If for any reason you are not satisfied with your purchase at FineArtAmerica.com/Pixel.com, you may return it within 30 days of the order date. Once it arrives, we will refund your full purchase price. Please note - FineArtAmerica does not cover the cost of outgoing or return shipping unless the reason for the return is a quality defect.
Returning your order is very easy, just fill in your email address and order number in this form.