Refund

I bought a bike for my child on Black Friday. I asked for a girl's bike from the store assistant. When i got home i saw it was a boy's bicycle. Took it back now and had pay a extra R150 for a girl's one, "because the barcode change's between a boy's bike and a girl's bike'. That I can understand, but reason I am back is because the staff gave me the wrong one in the first place!! Really that is the reason? I have to pay the normal price because the staff member was *********** or untrained. There is no manager in the front to assist, the "hokkie" is empty.