Faulty Online System

I recently started using the online purchase of cotton and their were red flags during my experience which I'd like to bring to their attention. The online system doesn't allow users to select two items when both are on sale, the invoice the user receives is different from the email and the delivery invoice, I close to an hour trying to explain it to the online chat consultant who kept on trying to convince me I was mistaken and that the sale was long over before I purchased. They than took the item offline which made me think why would you turn around and say I purchased late but you taking the item offline when I refused to accept they explanation they than offered me a discount on my next purchase and I refused it because they couldn't admit they system was wrong , I did receive my purchase at the end of the day. But how secure is my data if your system has bugs and how many other customers were wrongly billed by your system. I did save the conversation with the online consultant.