BUILDERS WAREHOUSE - TERRIBLE SERVICE

I must express my disappointment with Builders Warehouse Richards Bay. My partner and I are currently renovating our apartment and have been using Builders Warehouse for all our building needs. On saturday, we went to the Richards Bay store at Town Square to buy paint to match the existing wall colour. The recommendation was to mix the paint as closest to the sample. Unsure of the mixture I then enquired at the paypoint if I could return paint it if doesnt match the existing colour. The answer was a solid YES, provided that the slip is available and the paint can is not open. Today when I returned the paint with the slip in hand I was told Builders Warehouse does not accept mixed paint, its procedure. I am not against the procedure or policy but the principle, why was I not suffieciently informed that mixed paint is non returnable. I am not a paint expert , but if I was informed of the policy upfront that would have impacted the buying process. Its unacceptable that when driven to make a sale reps dont explain the full process to the client , yet on return procedure kicks in. We am now sitting with a 5 litre can of paint (which costed just below R400) that is of no use to us. I asked if I could take a different brand altogether for the same value so no monetary refund will be involved and it was denied. I really am disappointed.??? We are even changing stores completely for the rest of the renovation.