Worst customer service - Sales (parts) department

The worst customer service to date. I went to Nissan Randburg on Monday the 15th April 2019 to purchase an NP200 brake switch, they did not have any in stock. However, the sales man said they can order one for me, which will be delivered on Tuesday the 16th April 2019 in the afternoon. He then said, there'll call me to come get the switch tomorrow referring to the next day/16th provided that I pay for the switch before leaving their dealership because they cant place an order without payment. I paid and they issued me with an invoice, then I left. They never called me on the 16th, I called them today mid-day/17th April 2019 to follow up and I was then only informed that my switch was ready for collection. I then told them, I was coming to collect it. When I got there, they gave me the switch which looked similar to my old switch but it was bigger than my old switch. I then went to my car to get my old switch, while the new switch was still wrapped in its bag. I came back with both the old switch and the new switch to show them the difference, then the sales guy suggested that we go to their warehouse in the same premises to ask one their technicians about the difference between my old switch and the new switch. The technician confirmed that the switches are the same, size does not matter however, the new switch was slightly sensitive, as a result I should not press the front part. When I called my private technician he recommended that I should not insert the new switch but I should check if its working by only plugging it into the cable and putting my car on to check if the brake lights do come on. I did that and the lights didn't come on, then he told me there might be a problem with the new switch. When I went back into the dealership, to enquire the sales man pointed me to the electrical parts disclaimer and told me that I cant return the switch. When I asked him, if theres anyway possible to check if the switch is working he told me about the internal procedures (Job cards etc) of the workshop . Therefore, he told me they cant do anything for me and also suggested that I might've broke the new switch, to think that I never even left the dealership and I kept on asking a lot of questions before I took the switch out of its original bag, I found his behaviour to be very ********* and not customer focussed. Therefore, I'm extremely disappointed with Nissan's customer service (Parts - Sales) and totally regret owning one of it cars.