Unnoyed and inconvenienced

I bought an exercise set that had 4items....one of them was a yoga ball. The ball had a hole, I sent it back and I was asked to return the rest of the set which include 1kg dumbells, excercise step and resistance band.... Which all work fine but I don't understand why I have to return the other items when there's nothing wrong with them. Such an inconvenience looking for packaging, 4weeks laters, to get the things sent back... Which is unnecessary.