I'd check with the company that made them. Who knows, they might have good customer service and will accommodate you. CALL, don't email, if they have a customer service number.
What size are you? A lot of people have a wide foot and don't even know it. They just get a longer shoe/boot that doesn't fit right and wait for it to break in.
Regardless, you shouldn't need to break in any footwear for it to feel comfortable. Sounds like whatever you bought is too small or tight in a specific area.
I'm a 12.5W