Bad Customer Service!!!

My experience with Cross Trainer in Church Square Pretoria is really frustrating and inconveniencing. The sale assistant sold me a wrong shoe size and now that we go back to exchange for a bigger size they asked us to top it up and unfortunately we cannot so I requested for a refund and they said they had a no returns and refund policy. Now we are forced to choose a different brand shoes???? Of the same price??? Like how??? When we spoke to the manager she said the sales was supposed to have explained the policy to us and which they hadn't done so!!!! I'm so livid I will never again buy from any of their stores