Bad customer care

I have recently received my sneakers from the PumaSA online store and they did not fit me. I have been trying to get in touch with them via email and telephone with no luck at all. I want to return them and get a size that fits me but without a response at all from the customer care, it seems impossible. Their phone number just keeps ringing with no sign of an agent picking it up and no one is responding to emails, even their Instagram account DMs are unresponsive. This is by far the worst customer service EVER or lack thereof.