If they are leather - direct a hairdryer (hot setting)for about 30 seconds onto the part of the shoe that is tight and manipulate/stretch the shoe with the back of a spoon, pestle or your thumbs.
I am an avowed fan of Doc Marten shoes, I have worn them for about thirty years.
When the time comes to renew, and it is usually after at least ten years of daily wear, I accept that I need to break them in, and that once done, they will be wonderfully comfortable until they wear out.
As I say to the gentleman in Brassington's in Hanley where I buy my Docs, you have to suffer a little for iconic footwear.
Thanks for replies.
I have one foot bigger than the other. The right foot fits perfectly. The left foot has always been the problem as it is slightly smaller and wider, so it is slightly loose at the back and rubs on my heel and slightly smaller at the toe end (due to having a wider foot).
I could buy a half size bigger but that just reverses the problem!
(I would then have a right foot shoe scraping at my heel etc)
I dont have the luxury of breaking them in, in the house. I only have one pair of shoes to my name at the moment.
//If the back of my shoes are too stiff and they rub, I soften them by hitting them with the handle end of a large screwdriver//
My mum said something similar today...except she said a hammer ;-)