Wrong sim sent for phone

Did my upgrade online and after battling to get all the documentation in order as my contract is in my mother's name and she had to phone a couple offices to confirm everything. I finally received my phone a week later. So I open it up to get it'll setup and ready and to my horror the wrong size sim was with my phone. Now what are we going to do??? As I am now sitting with a new phone that can't be used. Lovely.