Poor service and not forthcoming

I visited De Kelder resturaunt in Plattekloof road today and must say it was not a pleasant experience. Other than the slow service received my frustration lies with the fact that I ordered a draft Alpha berry cider which one would generally expect to be a 500ml beverage but immediately noticed was not the case as it was served with approximately 250ml of the beverage and the rest ice. I then continued to order a second glass instructing the waitress not to add ice and received a gin glass filled to the 250ml mark with cider. When the bill came I was charged for 2x 500ml Alpha Berry ciders @ a cost for both was just over R70.00. Feeling hard done for receiving essentially 500ml of cider and the rest ice I continued to ask for the manager, Neels, which then argued that this was an instruction by the supplier after trying to demonstrate that I was wrong. His response to me was that should I only pay for the 500ml liquid draught that was served to me was that he would then deduct the other drink from the waitresses tips. How is this ethical ? I honestly am shocked at how you can falsely advertise drinks and then tell me it’s normal???