guys, thanks for all the comments and ideas.
actually, i called the consumer protection department (CPD)(toll free 8005000) 15 minutes after i bought and i made a complain and they gave me a reference number.
later they called and asked for a copy of my id and a copy of the receipt which i faxed the second day.
then they got back to me after 3 days saying that there is nothing i can do and the store is not obliged to return the item.
it is important to mention that CPD always publish in local newspapers announcements (i have the arabic copy) about the right of the customer for refund or exchange of items according to law number 8 in 2008.
Also it is very clear that the store is not allowed to put on the receipt “no refund or exchange” or anything similar.
I replied to CPD by saying that this store puts on all receipts exactly the following: “no refund! Exchange only within 2 days”, which contradicts very bluntly the CPD announcement and law.

Till now, I got no answer and I know this will lead nowhere but i want others to know so they will not get cheated by this store.

if you learn from your mistakes, you are smart;
if you learn from the mistakes of others, you are wise!

THANK YOU