sir cooper printing never delivered a usable product internet

i chose sir cooper for a 2'x3' poster that i needed for a client.   i waited for a proof but instead received the poster in the mail.  there was an error that was not caught because of receiving no proof.  i contacted them, and they offered a replacement.  i resent the file and the poster was shipped again, and this time was of extremely poor quality.  i contacted them again to let them know of the horrible color errors in the poster, and also sent them photos of the two side by side.   they promised a replacement, but it never came.  i contacted them to ask for my money back, but did not receive it.  they don't respond to my emails, but do continue to send me their promotional mailers.  i would never use this company again.  the quality of the work is shoddy, and the service slow to non-existent.  they are very dishonest.