Appalled by checkers gateway

I am deeply appalled by the service I was given an hour ago at checkers gateway by a cashier. I was assisted by Sanele on till number 2 on the express tills. I purchased a tub of g****s because of the special I saw for 1 for R39 and 2 for 50 so I took them. When I got to the till I used my extra savings card and the balance did not go down from R80 to R50 so I asked why and he told me he used the extra savings card he wouldn't know. I then proceeded to ask if he can find out. He then told me to go to the service desk and ask for a refund and closed the till and gave me my change and slip. I asked why he is closing the till while assisting me. He is said he is doing his job and I will not teach him his job. Then proceeded to say I took the wrong g****s and not the one on special. I told him I took them where there was a paper written "on special" he told me he wants to do his job and assist other customers. I had to take those g****s for R80 and leave with them. I feel like he should have told me that these g****s are not on special and these are on special so I can quickly change them if they are still available and not give me the attitude he gave me and this is not the first time as he did it last week however it was miner I payed no attention to it. I feel disrespectful by him.