You still can ask for discount even if you received the laptop but within the full refund period. Call Dell & nego kau-kau. 

yes cash! press 2  den 1.. tell him/her to transfer you to customer service dept.. and if he or she insists you to tell what happen.. say you are dissatisfied with your laptop ( avoid explaining so much to them cuz at the end they will transfer ur call to cs dept)    thats what happen to me..
before that take down the number near your battery. (service tag) or for those who still havent receive den you giv em your customer number stated in ur bill.

They say every week different promotion, they cannot keep giving previous customers rebates because of that.

I'm gonna receive my new Dell tomorrow. Thinking about returning it and then ordering again for the cheaper price, but it is very troublesome