Bad treatment

On Saturday I went to the restaurant for lunch with my girlfriend. I was allocated a table, I made an order. After I had eaten and having a chat with my girlfriend, a different waiter came to tell me that I should move to another table because the one we had was reserved for other people. I did not take that kindly, why was I not told before ordering that the table has been reserved, I did not ask to be seated there, I was allocated that table by the waiter. I found that rude. I am a paying customer and I deserve to be respected.