Truworths
Wrong shoe size on the wrong day

I went into truworths to buy a sandal and asked the lady for a size 7, thinking that it is a size 7 i wore it to a wedding but i could feel that the sandal does not sit right on me. i phone head office today and the dropped the phone twice in my ear, i just want my right size she because a paid R400 for it. what must i do with a size 8 sandal