Sale of unavailable stock

So i went to game heidelberg mall to buy the advertised sale of a 3×3 camp master gazebo that comes with 2× camp master chairs for the value of R999.. The gazebo was available in the shop and yet the said chairs were unavailable. My quiry is,if you bring stock of 200 gazebo and 400 camp chairs,then how do you run out of 400 chairs and yet have remaining gazebos on stock for sale??? I want the said gazebo that is on sale,along with the camp master chairs not what they told us that they have ran out of camp chairs but the gazebo is still available... Can game heidelberg mall care to explain because i do not buy this "while stock lasts" explanation when infact the gazebo is still available in the shop...