Price on the menu not correct

So i went to the drive-thru at the McDonald's at Westgate mall in Mitchell's plain about 10 minutes ago to buy me breakfast. The price of the mega mc****ib meal ie showing R49.99 on the menu outside. So i place my order and when I get to the window the lady tells me its R52.90. So i told her but the price on the menu is R49.99.

I asked for a manager and he said the prices has changed on the system but not on the menu's. So whose problem is that? The price i see is the price i pay. Any small struggling business follows this rule. However one of the biggest companies in the world cannot give into this. So i ended up purchasing nothing and went to buy breakfast at kfc.