Yeah they had no problems changing mine with the reciept when I got the wrong size.
You’ll need the next band size up for at least the first few weeks. I’m now 5WPO and now back into my normal size band. They are really fab bras tho!
Just to give you an idea on sizes aswell, I was a 32B I had 375/400 implants and change between the 34E & 32F in this bra. Xx