Zando wont refund me

Good day, I bought 3 pairs of shoes online at Zando. Upon recieval, 2 pairs were big I then lodged a return and sent an email asking if will it be possible to get another size I was told that they will and once shoes have been collected they will automatically ship them.Shoes were then collected and I have not heard anything from Zando.Been calling them and they not answering nor responding to my emails.Please assist me as I need my money.Zando has disappointed me.