Bought new trainers. They're not that different to ones I have had before. Standard adidas type thing. Dithered as they were expensive but I knew I would get tons of wear from them so took the plunge. Tried them on in the shop and was like walking on air. Wore them for the first time and was nearly crippled by blisters. They rub so badly at the back that I can barely wear them. Seems ridiculous to be limping around in pain but equally they cost a lot so I don't want to give up if there is anything I can do. I mostly live in trainers so not sure why these are such an issue. Any brilliant suggestions?