Do not shop here, damaged goods sold

I went to Builders Warehouse in Sunninghill, and i live in centurion, because they had stock of a gate motor, the Gemini motor. I purchased it and had to even ask them why the price on their site is different then the shelf, the nerve of them was to tell me to log onto my phone internet and prove what I seen. then I get home, get a professional to come and install the motor, which cost me lots of money, and the motor is not working. It does not move from auto to manual, just stays on manual all the time.

Now I been told that I cannot go to centurion to exchange, and have to go back where I bought it to exchange, and worst of all, I have now lost the money I paid for installation, and have to now pay the same people to come remove the motor,

Builders Warehouse has sold damaged goods, and are not willing to even help me by letting me exchange at a store closer to my house. Now I have even lost out on the money for installation and removal, Builders, why do you not test electronic items at your store before letting it leave the store? Is it because you know you are selling damaged goods to people right?