Completely ruined my Sister’s 21st Birthday

I had booked a private room for my sister’s 21st birthday. I had initially booked it for 9 people but I was advised I needed minimum 12 people or spend $1000 to be able to get the private room, I chose to book it for 12 people. As long as the room was not booked out on the day by someone willing to spend $1000, I was reassured the room will be available. I called a number of times before the actual date and was advised the same thing. I bought big balloons for decorations and a birthday cake for the occasion.When my family and I arrived on the day we got told we hadnt made a $250 deposit beforehand and there was enough staffing for us to get the private room even though the room was completely free and this information was not previously advised. The manager was completely rude kept stating she had other customers to serve and all they could do was shove us in some corner. My family and I have dined on many occasions in this restaurant and booked the private room without any hassle but THIS WAS THE LAST TIME WE WOULD EVER SET FOOT IN THIS RESTAURANT DUE TO THIS HORRENDOUS EXPERIENCE. COMPLETELY RUINED MY SISTER’s BIRTHDAY!!!