False and Misleading Advertising and no sense of service urgency

During Cyber Monday I bought 3 pairs of sneakers clearly labeled buy 3 and pay for 2, however when you add the item to the cart the 3 for 2 disappears and it does not discount. When you call online support the managers are always in a meeting. After 4 days of calling and holding a team leader by the name of Khanyisa called insisting that I need a screenshot of the cart showing 3 for 2, when I clearly said on my initial error which I logged the website shows 3 for 2 but once added to the cart it does not. I showed screenshots of the Website as well as the cart, yet she is still insisting. Do not lie to customers in terms of false advertising. The online support is not support, I received a mail query resolved when it was clearly not, this was 1 minute after it was stated my query is being attended to. I went through all the effort of screenshots etc. for absolutely nothing.