Ordered a size 3, received a size 7, and they don't give a f*ck

I ordered a size 3 shoe on the 28/08, upon receiving the order I noticed they had shipped a size 7 instead. I logged an exchange immediately, by which time they were sold out of the shoe I had ordered. So, I had to log an exchange and select the only other size available and explain my issue. I then spoke to Nicolette from client service, who did nothing about the matter. I received an email saying they were shipping a size 5 this yesterday, and complained and explained the issue and that they had messed up. To no avail, they're trying to make it seem like I'm in the wrong. The worst client service I've ever experienced, and they won't even own up to their mistake and try to sort it out. Pathetic!