Jet Kenilworth centre awful

I just came from jet, I went to return two of the items I bought a week ago, because it is small for me I would have taken a smaller size but just to be considerate for the workers time as the store was closing in the next 5 minutes I said they can return it instead,and I did not have the time to still seek and look for the right sizes or something else if not able to they the sizes. They said i can't return it because i purchased it as a buy two get third one free so it's like a gift to me from the company , I then told them I want to take the right sizes then if that's the case and still they said I cannot do that, they said I have to bring all the other items back then they can maybe do that , bluntly telling me it will be difficult so they can't do anything. I felt like I did not pay at all for anything when shopping by jet, and funny enough I hardly shopping by jet and I was happy when I did the purchase but after this I will not spend a single cent in that store again. Waste of time.