8 min imaginary period to return items yet its not noted on the slip.

Make it make ****ing sense, I bought wings and g****s. Wanted to exchange the g****s and return the wings. Got told I cant take these items back because the store will "make a loss". On the slip it says I can return these items until the 24th of March considering I paid at the food section why doesn't the slip have this imaginary 8 minute rule so that as customers we know what we are dealing with. HOW DISGUSTING. Where is it mentioned that the is a 8 min