I personally don't have this issue but I've had friends and readers in the past complain about the lack of choice in the market and how hard it can be some times to get a great boot for winter that fits correctly!
I've recently come across the UK web store Viva La Diva a store stocking wide width shoes and boots.
You can view a selection of Wide women's Boots and view styles by both foot width or calf size. Ranging from standard to EEE and calf sizes up to Extra Ultra Large you are sure to find a boot to suit your needs.
Here are a few styles on offer in the wide section :
Legroom Boots Extra Large Calf Fit - £75.00
Available in black or tan
Legroom Boots Extra Large Fit in Taupe (also in black) - £75.00
Jeffrey & Paula Stud Cowboy Boots (also in natural) - £75.00
Don't have wide feet? Not to worry you can browse so many other styles on this website. My current boot on this website that needs to be in my winter wardrobe is this pair of blue babies!
Daniel Wisdom Boot in Navy - £155.00