Unhappy Customer

I went to McDonalds Westgate Mall on 11th September to buy 2 big mac meals got there around 7PM went in the shop at 7h30 om it took them 30 mins to prepare my order and there was only about 10 people in store they are more worried about the drive through to get their food than those in store. When I asked to speak to the manager and explain the situation all she said was she's sorry, when I got home I got half my meal only instead of 2 burgers and 2 fries I only go 2 burgers and one fries, when I called I was told by Joy to come in the next day and fetch a complete big mac meals when I got there today had to wait 20mins for a manager she asked then why didn't I speak to the cashier who helped me last night with a **** attitude, I asked them instead of giving me a big mac meals to change it for a happy meal they refused it was my first time buying from McDonald's Westgate Mall but it was a terrible experience, store manager refused to give me her name when I said she cannot refuse all she then wrote on paper was Wandy.