The cross trainer east rand mall..... no no no

So last week i bought a pair of all stars all black from the cross trainer in east rand mall, when i paid at the counter the lady said, if they don't fit please come and swop them, i wore them once and felt they were too tight, so i came back and asked them to order me a bigger size, so today i came back and the shoes had arrived, the shoes i wore once had a bit of dust on the sole of the shoe and they refused to help me, she could have wiped it down and the shoes was as good as new instead she humiliated me infront of another customer and told me it's a lie and what if she had to do it for another customer and it's unprofessional. Again i wore them once and took them of, no scraches nothing just dust and she refused. I paid R700 for those shoes, what do i do with the shoes now. I feel that was unprofessional, i wont send anybody to that shop again to buy shoes. I feel the lady who told me i can bring them back should have been more clear, this is not a way to treat a customer.