Bad service

On the 28th September 2019 at 14L42 I was at McDonald`s Cape Gate and they did not have fizzy cooldrinks. I asked what do they have and they said only Milk Shakes and Ice Tea. They said that I will be responsible for the cost and when I addressed this with the manager, he said I must pay and it is not his problem that they don't have fizzy cooldrinks. He just turned around and walk away. Why must I as the customer pay for something that a huge franchise does not have and a manager of the franchise treat a customer so disrespectful? Is this the values McDonalds exercise to the clients and teach their managers? If they did not have fizzy drinks then McDonalds is responsible to carry the cost for whatever they offer the customer.