In reply to BusyLizzie:
If you can get to a shop with rock shoes then head over there turn the shoes upside down and try and match the shape of the shoe to the shape of your foot.
Square toes are hard to find a fit for, if you can find a shoe with laces all the way to the toe then this gives the ability to open up the toes more. However these type of shoe are not designed with the volume to have toes crunched up, the toes should be flat.
Things that might work include evolv royale, 5.10 anasazi guides, red chili sausalito or durango. Scarpa is wide too but further back towards the ball of the foot rather than across the toes.
However, it is best to try and find a good independent climbing shop where the staff are actual climbers, you can get lucky at larger chains but it's a bit pot luck!