Insolent behavior from staff at Builders Shelly Beach branch

Horrific experience today at Builder Express Shelly Beach branch located at the South Coast Mall. Went in, after extension online research to buy ducting piping. On their site, they had various ducting pipes listed in the various sizes. I approached the hardware counter and was serviced by a gentleman by the name of Mbuso. He mentioned to me that that item is only sold online. That is not what's stated on the site. He told me that they do not keep any ducting piping and yet after disputing his claims, he was able to produce ducting piping but not the size I wanted. What I'm really upset about is his colleague, a black lady with name starting with initial Z chipped into my conversation and told me I cannot read. I then asked for her manager and she refused to apologize. Her manager, Ockert Schonken came through after much deliberation and I feel handled the situation in the incorrect manner. The customer is always right and he should have asked the staff member to apologize. Instead he allowed her to Continue her insolent behavior. She was arrangant and defiant that I was the rude one. The customer is always right. You never tell a customer that he or she can't read. I hold 2 bachelor degrees. I'm absolutely upset and apalled by her behavior. I will never step foot into builders shelly Beach branch again. The employees involved need to be reprimanded and the manager sent for conflict handling training.