*** is an sku number? As a cust how should I know

Incredible connection advertised the Microsoft 1000 wireless mouse for R99. I came though all the way to Menlyn to purchase a red one. Only to find out it's only the black ones on sale. Then manager tells me, but it's printed in the fine print, it's an sku number of 83519 that's in sale.. Please explain as a customer how should I know what is an sku number? All I know is that you advertised the. Microsoft 1000 mouse for R99