Paying So much more for the same meal?

I get so many emails with Promo Codes, but the Promo Codes don't work? and the prices of the products are more than instore, plus delivery charges added. So what is the benefit of using Mr Delivery..not getting in the car? If I call in to the store to give my order - then there is no queue for me..so why pay so much extra for the same thing?