Unhappy client

First of all log in return is not user friendly,made a purchase online the bash app using payflex,unfortunately when the parcel arrived the shoe size was too bog wanted to exhange for a smaller size which is size 3 i went to foschini sammymarks square the cashiers couldn't exchange for me claiming payflex is not yet active at their store please TFG and Payflex resolve the matter I'm not happy as the size is out of stock online.