2l coke green cap replacement

Good day The 2L coke with returnable bottle for refund with the green cap . When buying a coke at the store there is always a problem if the bottle doesn't have the cap . Does it matter what cap it is replaced with? Why make it a issue when the bottle is returned with a different cap? Now if the store doesn't want to take the bottle what will i do with it? Meaning il dump it in the dustbin