Melangebox — Did not ship after 8 days and not taking my cancel order

Address:	Gurgaon
Website:	www.melangebox.com

I ordered 3 tshirts from Melangebox on 4th June. They had an option of paying through four installments through a gateway called Sezzle. After multiple reminders they had still not shipped my product till 9th June, so I asked them to cancel my order finally on 11th June. Now they are saying we can cancel if its not under transit but have not send any shipping notification. Also, they are not cancelling the order. They offer store credit and say that they don't refund the amount in case of returns..

(1)but why when they have not even shipped the product? ((2)) On contacting Sezzle they say they cant see any cancelled order and hence my next amount will be debited as per schedule. This means that I will not get my order, my entire amount will be debited, and then given back as store credit which I can never use since they do not ship the product at all?

Please help in cancelling the order and I want the refund back as well without any more deductions from sezzle