*** customer service

I made an online order and mistakenly added another item I didn't want and called Roman's pizza three-rivers Vereeniging immediately after getting a confirmation email email saying I can also call the the store should I want to make changes. I did and and I was directed to a white female female manager who told me that it can't be changed regardless of what the email said, I have to pay it. When I got to the store I showed her the email and she refused she gave me a nasty attitude became worse when I told her that I knew my consumer rights. I was forced to pay for something I didn't want and I will never ever buy anything from there infact I'm going to tell my friends and family about it.