We joined tonight and asked each for a starter and main

We joined tonight and asked each for a starter and main. The "Wurstsalat" was the under main menu. I said it's too much to eat 2 main. The waiter said it's fine you can eat it as a starter. We expected it then smaller. At the bill, we received it as full main charged and that was not what we agreed. The manager came on our table and said it must be a misunderstanding and he has no authority to reduce our bill because the owner"Rolf" is in hospital with lung infection. During our discussion, I said I knew the owner. Right I said this, the owner walked through the corner, hiding and thought I not see him. So the manager **** to us or the owner was not willing to sort the issue about the wrong bill out. Ridiculous