New bed and mattress

New bed and mattress for sale collection required I bought the bed and cotbed size mattress to move my daughter from cot to bed. It didn't work .. mattress is from baby elegance with spring pocket and bed is from IKEA. I bought a single mattress to use with the bed but it doesn't fit. They look the same as the one from the shop. I have bedsheets from IKEA and Zara, I won't need them so I can send them with the bed. All new. They were washed once, but again, everything new.