Very diasspointed customer

Much disappointed with Checkers Overport, The Atrium 430 Peter Makoba Road Overport Durban. i ordered Pampers baby Napkins that were on special with a 30% discount if i had purchased two packs from the store and made a payment was made online. Only to discover that when the deliver guy (sixty 60) delivers the nappies, he delivers one pack. Mind you my only reason was to take advantage of the 30% discount and special. to save money, the reason to request delivery was that i can order from the comfort my home. when i enquired from the delivery guy, i am told that the nappies are out of stock, mind you i was never contacted or notified that the nappies were out of stock. i would have bought them from some other store, Dischem or Clicks. Now they deliver one pack and i am charged the normal price per pack and i have lost out on the special. If the store is out of stock why don't they inform the customer and let the customer decide whether they are will to take the alternative offer. i have asked them to refund my money and i told that i should come to the store to proccess the refund which is not understandable because i have paid my hard earned money, if it was possible to get to the store i would have went there in the first place and bought the nappies. i am a very angry and dissapoint customer. and i advise people not to buy from this store via the sixty 60 app they are misleading their clients.