Exact - Refused exchange

I did a lay by at Exact Port shepstone and took my layby but some of the items did not fit and when i brought it back with a slip that they gave me they told me that they cant help me if i dont have the layby slip, so that means i am stuck with clothes that don't fit? Its worse i wanted to exchange for another size, what a ridiculous store, i am never shopping here again, your service is the worst of them all!