Exchange from baby registry

I am 35 weeks went in to exchange items I recieved on my baby registry from baby are us and they refused to assist me saying I need a slip, during this time all my gifts are being delivered to me and all my duplicates I normally exchange with no problem but today at baby r us centurion mall the manager was rude and never heard a word I said. They service is pathetic and I will never support them ever again as they have no understanding. How rude for me to ask the people who bought me gifts for the slip.