Did not give the customers change

I was ordering and paying for a chiproll paid for it by the manager of the store. I received the purchase slip with no change, after receiving the order slip I went and sat down. The food came I ate and completely forgot about the change. When done I left the store about 10m and realized I did not received the change. I went back to the manager, he said its to late now to ask for change as he forgot what I ordered. He went into the back came back and said I should leave my number at the end of the day they will call me to advise. No one called. I went back this morning to query what happened and the manager said nothing happened. I told him I will have to report him to Hello Peter, he went to the back a female voice shouted very loud rage, he came back and said that she said I can continue to report the incident.