Poor Service

On Saturday the 24th of October 2014 my friends and I went to have lunch at Cafe Vacca Matta as we love the restaurant but to our surprise a lot went wrong. We sat for over 45 minutes for a waiter and when a waiter was sent to serve us she refused - then later we were served but i didn't get his name then it took another hour for us to get our drinks and food. When we eventually got the food and drinks and we had to pay the bill, we were then forced to pay a 10% tip of which the waiter told us that a tip is compulsory, we cant just expect to eat and not tip. and my question is what is a tip? And he told us that it will depend on our bill but our bill was less then r500 but the receipt says a 10% Gratuity will be added to bill of r500 and above so why were forced to pay a tip after the poor service that we received.. Very disappointed because i considered your restaurant as one of my favorites but now i guess i have to stop coming there if the service is gong to slack like this.