Unlimited sneakers to return my tekkies

With several watsups and phone calls. I can't get a hold of unlimited sneakers. I ordered the wrong size and they advised me to return it and they will send me the right size. I did return it via postnet, but after that they didn't pick up my calls and no answer on watsup. I bought Nike of the value of R1700. I can't afford that money to go wasted.