bad service

I bought 7 items from MAKRO. when I got home I saw I only paid for 4. The till slip was checked at the door. I went back the next week to inform them about this and asked to talk to the manager of the store. They phoned him. but his reply was that the supervisor must handle it. I insisted to talk to him because I want to bring it under their attention if this could happen once how often does this happen. The manager send a person with a label on his shirt that said visitor. He refused to talk to me in my language and said he would only help me in his home language.. He was rude and had the lame excuse that their workers strike and they are under pressure. That is no excuse for not doing you work properly