it totally depends upon the item and what the arrangements are with the seller
I bought a play tent and then it wouldnt stand up unassisted. it was supposed to be free standing.
so i complained to the company and they told me to just keep the item and they would refund me.
come to think of it, this happened with a babysling i ordered too. from the pictures it looked like you could hold the baby hands free ( like when you push a pram and have a sling) but when it came it was more like a sling you had to cradle the baby in too, so i didnt have free hands for pushing the pram.