Bad service at McDonald's mall of Africa

Went to mall of Africa McDonald's, I wanted to join my order at the self service machine with a special on my mcdonald's account on my mobile phone. The lady at the counter named Lindiwe gave me very bad service. Didn't even want to hear what I wanted to do, didn't call for supervision because she couldn't merge my orders so I don't have to pay twice. She was dismissive.