Terrible After Sales Service

I ordered 2x smart rings for Fathers Day and checked the sized according to their size chart. Once the rings arrived they were too small. I have sent them 3x emails asking them to come and swop them for a size or two bigger. I got one reply that said they would get back to me in 48 hours time. I’ve emailed twice since then and even told them I will take this further if they don’t reply and they are ignoring me now. I need these for Fathers Day on Sunday and today is Friday and I still haven’t heard from them? I’ve asked for my money back twice now and still not reply! I need this sorted before Sunday!!