Info not disclosed in the slip

I laybyed a phone at dunns last week n this morning I wanted to pay in full I went to the store and I was told to come back later at 09:05 am so I went to another store and saw another phone and decided to buy it because I had a meeting on zoom at 9..I went back to dunns and told them I nolonger want it I want to cancel it the manager told me I can't cancel it unless I wait for the laybye to expire...I've never heard of such and Its not even written in their slip.