Customer service and service delivery

I received a voucher on 26 August 2015 at 19h34, I went to Checkers Liquor to redeem my voucher. When I entered my Wicode, it didnt work. The cashier asked the manager what she she should do, he did not even allow her to speak finish, before he answered her in a very rude manner. I gave her my phone to let him see the sms, he just put my phone one side, while she had to ask her 1 more time, what the customer should do?<br> The service I received was pathetic and that from a manager who has no customer service ethics. I was so disgusted , and decided to just walk away.