Disappointing experience

I bought sneakers on Wednesday online, I paid using eft and sent the proof of payment immediately to their email *** but up until today I’m getting emails saying my payment is outstanding and my order will be canceled if I don’t pay. I have been trying to call them and got hold of them on Thursday and they promised it will be sorted on Friday morning but that didn’t happen and now their number is going straight to voicemail. I sent an email stating my issue and disappointment with the service but there is no response to except for the email that reminds me twice a day that my payment is due.