Returning Nightmare

I'm so frustrated. I've bought myself some sneakers Online from Office London. I went to pick it up yesterday at my preferred store. Today I went to the store to return the sneakers because they're too big for me. The lady at the store advised me that I can't return them there by them, I need to go to a store where it's being sold. I don't understand, because on my slip it states that you can return it to any Truworths store but then you'll be charge a R25 handling fee. Please tell me what is your procedure regarding that. If I knew I was going to have such a hassle returning it, I would've never bought from Office London.