Undeliverd goods

I bought a dress via PayJustNow and I am nearing my second installment, and I haven't received my dress. I received an email on Friday night saying my dress would be dispatched on Monday, 20th April, but nothing. I have been blocked on WhatsApp and my emails not responded to. And I cannot blocked the upcoming payment from PayJustNow because they say they cannot prevent the merchant from getting their money. So Leigh Schubert is using PayJustNow to **** customers and they dont do anything about it.