I used
One Vision for a few larger prints based on Clive's (Gidders) recommendation. They provide a free colour match service whereas ProAm print as given which is fine once you have found the right spot. One Vision are very expensive for small prints but become cheaper for the larger sizes. I had
this printed at 12" x 12" which cost £4 and then professional mounted and framed (16x16 frame). In Hindsight I probably could on gone for a print of 16" x 16" and put into a 20" x 20" frame.