Made to feel like I was lying

I wentto N1City store today. I have been a client for over 20 years, and dont have a card with a magnetic strip. I enquired when I paid for my purchase how I go about getting a new card. I was told they need to get authorisation from their head office. I waited for about 10 min for them to get through. In the mean time the cashier went on to attend to other customers right next to me. That was fine I had no objection to that. However once your head office answered the cashier, she firstly told them I had lost my card which was not true. I was then handed the phone and had to answer security questions, with customers standing right next to me. The cashier, told by her in front of all the customers I had failed the test. I was so embarrassed. I felt that everybodying thought I was lying. I was told to bring in my ID and proof of add in order for them to verify my details. The cashier had already seen my id and I dont walk around with proof of address. I was also reminded that I can no longer use my acc.All this was conveyed in a very abrupt manner.If you dont want my business tell me I will close my acc. I get calls to tell what a good client I am, when u want to sell me a product