If it hasn't been confirmed within 2-3 days, you likely have no order to cancel.  Best first step is to call  your credit card company -- chances are the payment never went through.  
I placed an order on 31/07/20 via the Dell India website for a New Inspiron 14 5490 Laptop, and have an order acknowledgement email but no order confirmation email. I have an Internet Receipt Number but no Order Number, hence I have no way of contacting Order Support because all avenues on the Dell AU website seem to require having an Order Number first. Please advise on how I can follow up on my order. Or if it is possible to cancel this order, then please let me know how to do so. Thanks in advance!
No order confirmation email after 11 days